Wafer level light-emitting diode array

ABSTRACT

A light emitting device including a substrate, first and second light emitting diodes (LEDs) each including first and second semiconductor layers, a first upper electrode disposed on the second LED, electrically connected to the first LED, and insulated from the second semiconductor layer of the first LED, and a second upper electrode disposed on the second LED, electrically connected to the second LED, and insulated from the second semiconductor layer of the second LED, in which a portion of the substrate between the LEDs does not overlap the semiconductor layers, the first upper electrode has a portion electrically connected to the second semiconductor layer of the second LED and covering the first portion and portions of the LEDs, and the second upper electrode has a groove partially enclosing the portion of the first upper electrode in a plan view.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/858,560, filed on Apr. 24, 2020, now issued as U.S. Pat. No.11,139,338 on Oct. 5, 2021, which is a continuation of U.S. patentapplication Ser. No. 15/835,326, filed on Dec. 7, 2017, now issued asU.S. Pat. No. 10,804,316 on Oct. 13, 2020, which is a continuation ofU.S. patent application Ser. No. 15/081,134, filed on Mar. 25, 2016, nowissued as U.S. Pat. No. 10,388,690 on Aug. 20, 2019, which is acontinuation-in-part of, and claims the benefits and priorities to, U.S.patent application Ser. No. 14/420,175, filed on Feb. 6, 2015, nowissued as U.S. Pat. No. 9,318,530 on Apr. 19, 2016, which is the U.S.National Stage entry of International Application No. PCT/KR2013/007091,filed on Aug. 6, 2013, which further claims the benefits and prioritiesof prior Korean Patent Application No. 10-2013-0088710, filed on Jul.26, 2013, prior Korean Patent Application No. 10-2013-0088709, filed onJul. 26, 2013, prior Korean Patent Application No. 10-2012-0094107,filed on Aug. 28, 2012, and prior Korean Patent Application No.10-2012-0086329, filed on Aug. 7, 2012. U.S. patent application Ser. No.15/081,134 is also a continuation-in-part of, and claims the benefitsand priorities to, U.S. patent application Ser. No. 14/722,011, filed onMay 26, 2015, now issued as U.S. Pat. No. 9,318,529 on Apr. 19, 2016,which is a continuation-in-part of U.S. patent application Ser. No.14/426,723, filed on Mar. 6, 2015, now issued as U.S. Pat. No. 9,412,922on Aug. 9, 2016, which is the U.S. National Stage Entry of InternationalApplication No. PCT/KR2013/007105, filed on Aug. 6, 2013, which furtherclaims the benefits and priorities of prior Korean Patent ApplicationNo. 10-2012-0099263, filed on Sep. 7, 2012, prior Korean PatentApplication No. 10-2012-0101716, filed on Sep. 13, 2012, prior KoreanPatent Application No. 10-2013-0088712, filed on Jul. 26, 2013, priorKorean Patent Application No. 10-2013-0088714, filed on Jul. 26, 2013,and prior Korean Patent Application No. 10-2014-0063157, filed on May26, 2014, each of which is incorporated by reference for all purposes asif set forth herein.

BACKGROUND Field

Exemplary embodiments/implementations of the invention relate generallyto a light emitting diode array, and, more specifically, to a lightemitting diode array with a plurality of light emitting diodes connectedthrough wires and formed into a flip chip type.

Discussion of the Background

A light emitting diode is a device for performing a light emittingoperation when a voltage of a turn-on voltage or more is applied theretothrough anode and cathode terminals thereof. Generally, the turn-onvoltage for causing the light emitting diode to emit light has a valuemuch lower than the voltage of a common power source. Therefore, thelight emitting diode has a disadvantage in that it cannot be useddirectly under the common AC power source of 110V or 220V. The operationof the light emitting diode using the common AC power source requires avoltage converter for lowering the supplied AC voltage. Accordingly, adriving circuit for the light emitting diode should be provided, whichbecomes one factor causing fabrication costs of an illuminatingapparatus including the light emitting diode to be increased. Since adiscrete driving circuit should be provided, the volume of theilluminating apparatus is increased and unnecessary heat is generated.In addition, there are problems such as improvement of a power factorfor the supplied power.

To use the common AC power source in a state where a discrete voltageconverting means is excluded, there has been suggested a method ofconstructing an array by connecting a plurality of light emitting diodechips in series to one another. To implement the light emitting diodesas an array, the light emitting diode chips should be formed intoindividual packages. Thus, a substrate separating process, a packagingprocess for a separated light emitting diode chip, and the like arerequired, and a mounting process of arranging the packages on an arraysubstrate and a wiring process for forming wirings between electrodes ofthe packages are additionally required. Therefore, there are problems inthat a processing time for constructing the array is increased, andfabrication costs of the array are increased.

Moreover, wire bonding is used for the wiring process of forming thearray, and a molding layer for protecting bonding wires is additionallyformed on an entire surface of the array. Accordingly, there is aproblem in that a molding process of forming the molding layer isadditionally required, resulting in increase in the complexity ofprocesses. Particularly, in a case of application of a chip type with alateral structure, the light-emitting performance of the light emittingdiode chip is lowered, and the quality of the light emitting diode isdeteriorated due to the generation of heat.

SUMMARY

Some implementations of the disclosed technology in this patent documentprovide a flip-chip type light emitting diode array that can be drivenat a high voltage.

Some implementations of the disclosed technology provide a lightemitting diode array that can be mounted directly on a printed circuitboard or the like without any submount substrate.

Some implementations of the disclosed technology provide a flip-chiptype light emitting diode array that can prevent light loss withoutusing a discrete reflective metal layer in addition to wires forconnecting a plurality of light emitting diodes.

Some implementations of the disclosed technology provide a lightemitting diode array that can prevent cracks from occurring in layerscovering light emitting diodes, thereby improving the reliabilitythereof.

Some implementations of the present disclosure provide a flip-chip typelight emitting diode array capable of reducing a light loss to improvelight extraction efficiency.

Some implementations of the present disclosure provide a flip-chip typelight emitting diode array capable of effectively diffusing a current.

In one aspect, a light emitting diode array is provided to comprise: asubstrate, light emitting diodes positioned over the substrate, eachlight emitting diode including a first semiconductor layer, an activelayer, and a second semiconductor layer, wherein each light emittingdiode is disposed to form a first via hole structure exposing a portionof the corresponding first semiconductor layer; lower electrodesdisposed over the second semiconductor layer of corresponding lightemitting diodes, a first interlayer insulating layer disposed over thelower electrodes and configured to expose the portion of the firstsemiconductor layer of corresponding light emitting diodes, and upperelectrodes formed over the first interlayer insulating layer andelectrically connected to the first semiconductor layer of correspondinglight emitting diodes through the first via hole structures, wherein thefirst via hole structure of each light emitting diode is disposed inparallel with one side of the corresponding second semiconductor layer,and the first interlayer insulating layer is disposed to form second viahole structures exposing a portion of the lower electrodes ofcorresponding light emitting diodes.

In some implementations, the first via hole structure of a given lightemitting diode includes a pair of via holes disposed near edges of thegiven light emitting diode and a connection part connecting the pair ofvia holes, and one of the pair of via holes is spaced apart by apredetermined distance from at least one of the second via holes. Insome implementations, the first via hole structure has a dumbbell shape,a rectangular shape, or a rectangular shape with round corners. In someimplementations, the first via hole structure has a length proportionalto a length of a longer side of the second semiconductor layer. In someimplementations, the first via hole structure for at least one of thelight emitting diodes is disposed in a middle region of thecorresponding second semiconductor layer. In some implementations, thefirst via hole structure has a length ranging from no less than 30% toless than 100% of a length of one side of the second semiconductorlayer. In some implementations, at least one of the upper electrodes iselectrically connected to a second semiconductor layers of correspondinglight emitting diodes, and at least one of the upper electrodes isinsulated from the second semiconductor layers of the correspondinglight emitting diodes. In some implementations, at least one of theupper electrodes is electrically connected to the second semiconductorlayer of the corresponding light emitting diodes through the exposedportions of the lower electrodes. In some implementations, the lightemitting diode array further comprises: a second interlayer insulatinglayer covering the upper electrodes, wherein the second interlayerinsulating layer is disposed to form third via hole structures exposinga portion of the corresponding lower electrodes and a portion of thecorresponding upper electrodes. In some implementations, at least two ofthe third via hole structures are symmetrical with respect to thecorresponding first via hole structures in a given light emitting diode.In some implementations, the third via hole structures are spaced apartby a predetermined distance from a portion of the corresponding firstvia hole structure in a given light emitting diode. In someimplementations, the light emitting diode array further comprises: firstand second pads positioned over the second interlayer insulating layer,wherein the light emitting diodes are connected in series by the upperelectrodes, and the first pad is connected to the exposed portion of thecorresponding lower electrodes and the second pad is connected to theexposed portion of the corresponding upper electrodes. In someimplementations, the upper electrodes include ohmic contact layersproviding ohmic-contacts with the first semiconductor layers. In someimplementations, the upper electrodes further include reflective layerspositioned over the ohmic contact layers. In some implementations, eachof the lower electrodes includes a reflective layer. In someimplementations, at least one of the upper electrodes occupies an areano less than 30% and less than 100% of an entire area of the lightemitting diode array. In some implementations, at least one of the upperelectrodes has a length or a width greater than that of thecorresponding light emitting diode.

In another aspect, a light emitting diode array is provided to comprise:a substrate; light emitting units respectively disposed in a firstregion and a second region, each light emitting unit including a firstsemiconductor layer, an active layer, and a second semiconductor layer,wherein the light emitting units in the first and second regions aredisposed to form first via structures to expose a portion of thecorresponding first semiconductor layers; lower electrodes disposed overthe light emitting units in the first region and the second regionexcept the exposed portion of the first semiconductor layer; interlayerinsulation layers disposed over the lower electrodes to form second viastructures to expose a portion of the exposed portion of the firstsemiconductor layer, wherein the interlayer insulating layers arefurther disposed to expose a portion of the lower electrodes; and upperelectrodes disposed over the interlayer insulation layers, wherein oneof the upper electrodes is disposed in the first region to electricallyconnect the first semiconductor layer of the corresponding lightemitting unit in the first region to the second semiconductor layer ofthe corresponding light emitting unit in the second region.

In some implementations, at least one of the first via structuresincludes a pair of holes disposed at ends of the at least one of thefirst via structures and a connection part connecting the pair of holes.In some implementations, the first region and the second region arespaced apart and the upper electrodes are spaced apart to shield spacesbetween the first region and the second region. According to someembodiments of the disclosed technology, it is possible to provide alight emitting diode array on a wafer level, which can be driven at ahigh voltage and can be mounted directly on a printed circuit board orthe like. For example, since light emitting diodes of the light emittingdiode array are connected in series by upper electrodes, a submountsubstrate is not required. Since the upper electrode can include anohmic contact layer, it is not necessary to form a separate ohmiccontact layer.

In addition, side surfaces of the light emitting diodes are formed to beinclined at a predetermined angle, so that it is possible to provide aflip-chip type light emitting diode array on a wafer level, which hasimproved reliability. Further, the side surfaces of the lowerelectrodes, first interlayer insulating layer, upper electrodes orsecond interlayer insulating layer are formed to be inclined at apredetermined angle, so that it is possible to prevent cracks from beingproduced in another layer formed on the respective layers.

Further, since the upper electrodes occupy a relatively large area, andalso cover side surfaces of the light emitting diodes and most of theregions between the light emitting diodes, the upper electrodes can beused to reflect light. Thus, it is possible to reduce a loss of lightgenerated in the regions between the light emitting diodes. Therefore,it is not necessary to additionally form a separate reflective metallayer for reflecting light, in addition to the upper electrodes.

Furthermore, the upper electrodes are made in the form of a plate orsheet having a wide area, thereby improve current distributionperformance and decreasing a forward voltage at an identical currentwhile using an identical number of light emitting diodes.

Moreover, the current diffusion performance of the light emitting diodemay be improved by the appropriate disposition and form of the viaholes, thereby improving the overall current diffusion performance ofthe light emitting diode array.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 and 2 are plan and sectional views showing that a plurality ofvia hole structures are formed in a laminated structure according to anembodiment of the disclosed technology.

FIGS. 3 and 4 are plan and sectional views showing that lower electrodesare formed on a second semiconductor layer of FIG. 1 .

FIG. 5 is a plan view showing a state where cell regions are separatedwith respect to the structure of FIG. 3 .

FIG. 6 is a sectional view taken along line A1-A2 in the plan view ofFIG. 5 .

FIG. 7 is a perspective view of the structure in the plan view of FIG. 5.

FIG. 8 is a plan view showing that a first interlayer insulating layeris formed on an entire surface of the structure of FIGS. 5 to 7 , andportions of a first semiconductor layer and the lower electrodes areexposed in each of the cell regions.

FIGS. 9, 10, 11, and 12 are sectional views taken along specific linesin the plan view of FIG. 8 .

FIG. 13 is a plan view showing that upper electrodes are formed on thestructure illustrated in FIGS. 8, 9, 10, 11, and 12 .

FIGS. 14, 15, 16, and 17 are sectional views taken along specific linesin the plan view of FIG. 13 .

FIG. 18 is a perspective view of the structure in the plan view of FIG.13 .

FIG. 19 is an equivalent circuit diagram obtained by modeling thestructure of FIGS. 13 to 18 according to one embodiment of the disclosedtechnology.

FIG. 20 is a plan view showing that a second interlayer insulating layeris applied on an entire surface of the structure of FIG. 13 , a portionof a first electrode in a first cell region is exposed, and a portion ofa fourth lower electrode in a fourth cell region is exposed.

FIGS. 21, 22, 23, and 24 are sectional views taken along specific linesin the plan view of FIG. 20 .

FIG. 25 is a plan view showing that first and second pads are formed inthe structure of FIG. 20 .

FIGS. 26, 27, 28, and 29 are sectional views taken along specific linesin the plan view of FIG. 25 .

FIG. 30 is a perspective view taken along line C2-C3 in the plan view ofFIG. 25 .

FIG. 31 is a circuit diagram obtained by modeling a connection of tenlight emitting diodes in series according to an embodiment of thedisclosed technology.

FIG. 32 is a circuit diagram obtained by modeling an array having lightemitting diodes connected in series/parallel according to an embodimentof the disclosed technology.

FIGS. 33 and 34 are a plan view and a sectional view showing that firstvia holes are formed in a plurality of laminated structures according toan embodiment of the present disclosure.

FIGS. 35 and 36 are a plan view and a sectional view showing that lowerelectrodes are formed on a second semiconductor layer of FIG. 33 .

FIG. 37 is a plan view showing a state where cell regions are separatedwith respect to the structure of FIG. 35 .

FIG. 38 is a sectional view taken along line A1-A2 in the plan view ofFIG. 37 .

FIG. 39 is a perspective view of the structure in the plan view of FIG.37 .

FIG. 40 is a plan view showing that the first interlayer insulatinglayer is formed on an entire surface of the structure of FIGS. 37 to 39, and portions of the first semiconductor layer and the lower electrodesare exposed in each of the cell regions.

FIGS. 41, 42, 43, and 44 are sectional views taken along specific linesin the plan view of FIG. 40 .

FIG. 45 is a plan view showing that the upper electrodes are formed onthe structure illustrated in FIGS. 40, 41, 42, 43, and 44 .

FIGS. 46, 47, 48, and 49 are sectional views taken along specific linesin the plan view of FIG. 45 .

FIG. 50 is a perspective view of the structure in the plan view of FIG.45 .

FIG. 51 is an equivalent circuit diagram obtained by modeling thestructure of FIGS. 45 to 50 according to a preferred embodiment of thepresent disclosure.

FIG. 52 is a plan view showing that the second interlayer insulatinglayer is applied on an entire surface of the structure in the plan viewof FIG. 45 , a portion of the first lower electrode in the first cellregion is exposed, and a portion of the fourth lower electrode in thefourth cell region is exposed.

FIGS. 53, 54, 55, and 56 are sectional views taken along specific linesin the plan view of FIG. 52 .

FIG. 57 is a plan view showing that the first and second pads are formedin the structure of FIG. 52 .

FIGS. 58, 59, 60, and 61 are sectional views taken along specific linesin the plan view of FIG. 57 .

FIG. 62 is a perspective view of the structure in the plan view of FIG.57 .

FIG. 63 is a sectional view taken along line C2-C3 in the perspectiveview of FIG. 62 .

FIG. 64 is a perspective view showing a light emitting diode moduleincluding a light emitting diode array according to an embodiment of thepresent disclosure.

FIG. 65 is a circuit diagram obtained by modeling a connection of tenlight emitting diodes in series according to an embodiment of thepresent disclosure.

FIG. 66 is a circuit diagram obtained by modeling the array having lightemitting diodes connected in series/parallel according to an embodimentof the present disclosure.

FIGS. 67 and 68 are plan and sectional views showing that a plurality ofvia holes are formed in a laminated structure according to an embodimentof the present disclosure.

FIGS. 69 and 70 are plan and sectional views showing that lowerelectrodes are formed on a second semiconductor layer of FIG. 67 .

FIG. 71 is a plan view showing a state where cell regions are separatedwith respect to the structure of FIG. 69 .

FIG. 72 is a sectional view taken along line A1-A2 in the plan view ofFIG. 71 .

FIG. 73 is a perspective view of the structure in the plan view of FIG.71 .

FIG. 74 is a plan view showing that a first interlayer insulating layeris formed on an entire surface of the structure of FIGS. 71 to 73 , andportions of a first semiconductor layer and the lower electrodes areexposed in each of the cell regions.

FIGS. 75, 76, 77, and 78 are sectional views taken along specific linesin the plan view of FIG. 74 .

FIG. 79 is a plan view showing that upper electrodes are formed on thestructure illustrated in FIGS. 74, 75, 76, 77, and 78 .

FIGS. 80, 81, 82, and 83 are sectional views taken along specific linesin the plan view of FIG. 79 .

FIG. 84 is a perspective view of the structure in the plan view of FIG.79 .

FIG. 85 is an equivalent circuit diagram obtained by modeling thestructure of FIGS. 79 to 84 according to an embodiment of the presentdisclosure.

FIG. 86 is a plan view showing that a second interlayer insulating layeris applied on an entire surface of the structure of FIG. 79 , a portionof a first electrode in a first cell region is exposed, and a portion ofa fourth lower electrode in a fourth cell region is exposed.

FIGS. 87, 88, 89, and 90 are sectional views taken along specific linesin the plan view of FIG. 86 .

FIG. 91 is a plan view showing that first and second pads are formed inthe structure of FIG. 86 .

FIGS. 92, 93, 94, and 95 are sectional views taken along specific linesin the plan view of FIG. 91 .

FIG. 96 is a perspective view taken along line C2-C3 in the plan view ofFIG. 91 .

FIG. 97 is a circuit diagram obtained by modeling a connection of tenlight emitting diodes in series according to an embodiment of thepresent disclosure.

FIG. 98 is a circuit diagram obtained by modeling an array having lightemitting diodes connected in series/parallel according to an embodimentof the present disclosure.

DETAILED DESCRIPTION

In order to solve problems associated with the conventional array oflight emitting diodes, there has been proposed a light emitting diodechip array in which an array including a plurality of light emittingdiode chips is fabricated as a single package.

In Korean Patent Laid-Open Publication No. 2007-0035745, a plurality oflateral type light emitting diode chips are electrically connected on asingle substrate through metal wiring formed using an air bridgeprocess. According to this laid-open publication, there is an advantagein that a discrete packaging process is not required for each of theindividual chips, and an array is formed on a wafer level. However, theair bridge connection structure results in weak durability and thelateral type causes a problem of deterioration of the light-emittingperformance or heat-dissipating performance.

In U.S. Pat. No. 6,573,537, a plurality of flip-chip type light emittingdiodes is formed on a single substrate. However, n- and p-electrodes ofeach of the light emitting diodes are exposed to the outside in a statewhere the n- and p-electrodes are separated from each other. Therefore,a wiring process of connecting a plurality of electrodes to one anothershould be added in order to use a single power source. To this end, asubmount substrate is used. That is, the flip-chip type light emittingdiodes should be mounted on a discrete submount substrate for wiringbetween the electrodes. At least two electrodes for electricalconnection with another substrate should be formed on a back surface ofthe submount substrate. In the US patent, since the flip-chip type lightemitting diodes are used, there is an advantage of improvement of thelight-emitting performance and heat-dissipating performance. On thecontrary, the use of the submount substrate causes increase in bothfabrication costs and the thickness of a final product. In addition,there are further disadvantages of needs for an additional wiringprocess for the submount substrate and an additional process of mountingthe submount substrate on a new substrate.

Korean Patent Laid-Open Publication No. 2008-0002161 discloses aconfiguration in which flip-chip type light emitting diodes areconnected in series to one another. According to the laid-open patentpublication, a packaging process on a chip basis is not required, andthe use of the flip-chip type light emitting diodes exhibits an effectof improvement of the light-emitting performance and heat-dissipatingperformance. However, a discrete reflective layer is used in addition towiring between n-type and p-type semiconductor layers, andinterconnection wiring is used on the n-type electrode. Therefore, aplurality of patterned metal layers should be formed. To this end,various kinds of masks should be used, which becomes a problem. Inaddition, exfoliation or crack occurs due to a difference in thermalexpansion coefficient between the n-electrode and the interconnectionelectrode, or the like, and therefore, there is a problem in thatelectrical contact therebetween is opened.

Hereinafter, various embodiments of the disclosed technology areprovided to provide a novel light emitting diode array. The embodimentsof the disclosed technology will be described in greater detail withreference to the accompanying drawings. The disclosed technology is notlimited to the following embodiments but may be implemented in otherforms.

In these embodiments, it will be understood that the term “first”,“second”, “third” or the like does not impose any limitation oncomponents but are only used to distinguish the components.

FIGS. 1 and 2 are plan and sectional views showing that a plurality ofvia hole structures are formed in a laminated structure according to anembodiment of the disclosed technology.

In particular, FIG. 2 is a sectional view taken along line A1-A2 in theplan view of FIG. 1 .

Referring to FIGS. 1 and 2 , a first semiconductor layer 110, an activelayer 120 and a second semiconductor layer 130 are formed on a substrate100, and via holes 140 are formed to allow a surface of thesemiconductor layer 110 to be exposed therethrough.

The substrate 100 comprises a material such as sapphire, silicon carbideor GaN. Any material may be used for the substrate 100 as long as it caninduce the growth of a thin film to be formed on the substrate 100. Thefirst semiconductor layer 110 may have n-type conductivity. The activelayer 120 may have a multiple quantum well structure, and the secondsemiconductor layer 130 is formed on the active layer 120. When thefirst semiconductor layer 110 has the n-type conductivity, the secondsemiconductor layer 130 has p-type conductivity. A buffer layer (notshown) may be further formed between the substrate 100 and the firstsemiconductor layer 110 so as to facilitate single crystalline growth ofthe first semiconductor layer 110.

Subsequently, selective etching is performed on the structure formedwith the second semiconductor layer 130, and a plurality of via holestructures 140 are formed. Portions of the lower first semiconductorlayer 110 are exposed through the via hole structures 140. The via holestructures 140 may be formed through a conventional etching process. Forexample, a photoresist is applied, and portions of the photoresist onregions where the via hole structures will be formed are then removedthrough a conventional patterning process to form a photoresist pattern.Thereafter, an etching process is performed by using the photoresistpattern as an etching mask. The etching process is performed until theportions of the first semiconductor layer 110 are exposed. After theetching process, the photoresist pattern remaining is removed.

The via hole structures 140 have a range of inclination angles (a) withrespect to a surface of the substrate or a surface of the firstsemiconductor layer 110, which is exposed by performing the etchingprocess. In particular, if the via hole structures 140 do not have arange of inclination angles, in a subsequent process of vapor-depositinga metal or applying an insulation material, cracks may be produced in adeposited metal layer or applied insulation material layer. Even thoughno crack is produced in a fabrication process, a problem of reliabilityis caused when a light emitting diode is used later. Heat and electricalstress generated when the light emitting diode emits light according tothe supply of electrical power cause cracks to be produced in metal orinsulation material layers formed on the via hole structures 140 beyondthe particular inclination angle (a). The produced cracks causemalfunction of the light emitting diode and thus a decrease inluminance.

In some implementations, the via hole structures 140 have an angle of 10to 60 degrees with respect to the surface of the substrate 100 or thesurface of the first semiconductor layer 110.

If the inclination angle (a) is less than 10 degrees, the area of theactive layer 120 is decreased due to an excessively low slope. Thedecrease in the area of the active layer causes a decrease in luminance.The substantial area of the second semiconductor layer 130 is muchsmaller than that of the first semiconductor layer 110. Generally, thesemiconductor layer 130 has p-type conductivity, and the firstsemiconductor layer 110 has n-type conductivity. When the light emittingdiode emits light, the first semiconductor layer 110 supplies electronsto the active layer 120, and the second semiconductor layer 130 suppliesholes to the active layer 120. The improvement of light-emittingefficiency tends to rely on the uniform and smooth supply of holesrather than the supply of electrons. Thus, an excessive decrease in thearea of the second semiconductor layer 130 may cause the light-emittingefficiency to be lowered. In a case where the inclination angle (a)exceeds 60 degrees, cracks may be produced in a subsequent metal orinsulation material layer due to a high slope.

Meanwhile, the shape and number of the via hole structures 140 may bevariously changed.

FIGS. 3 and 4 are plan and sectional views showing that lower electrodesare formed on the second semiconductor layer of FIG. 1 . Particularly,FIG. 4 is a sectional view taken along line A1-A2 in the plan view ofFIG. 3 .

Referring to FIGS. 3 and 4 , the lower electrodes 151, 152, 153 and 154are formed in regions except the via hole structures 140, and aplurality of cell regions 161, 162, 163 and 164 may be defined by theformation of the lower electrodes 151, 152, 153 and 154. The lowerelectrodes 151, 152, 153 and 154 may be formed by employing a lift-offprocess used upon formation of a metal electrode. For example, aphotoresist is formed in separating regions excluding the virtual cellregions 161, 162, 163 and 164 and in the regions in which the via holestructures 140 are formed, and a metal layer is formed throughconventional thermal deposition or the like. Subsequently, thephotoresist is removed, thereby forming the lower electrodes 151, 152,153 and 154 on the second semiconductor layer 130. Any material may beemployed for the lower electrodes 151, 152, 153 and 154 as long as it isa metallic material capable of being in ohmic contact with the secondsemiconductor layer 130. The lower electrodes 151, 152, 153 and 154 maycomprise Ni, Cr or Ti, and may be composed of or include a compositemetal layer of Ti/Al/Ni/Au.

The lower electrodes 151, 152, 153 and 154 may have thicknesses in arange of 2000 to 10000 Å. If the thicknesses of the lower electrodes151, 152, 153 and 154 are less than 2000 Å, the reflection of light fromthe lower electrodes 151, 152, 153 and 154 toward the substrate 100 isnot smooth, and there is a leakage of light transmitted through thelower electrodes 151, 152, 153 and 154 in the form of thin films. If thethicknesses of the lower electrodes 151, 152, 153 and 154 exceed 10000Å, there is a problem in that it takes an excessive amount of time toperform a process of forming the lower electrodes, such as thermaldeposition.

The lower electrodes 151, 152, 153 and 154 may have inclination angles(b) of 10 to 45 degrees with respect to the surface of the secondsemiconductor layer 130. If the inclination angles (b) of the lowerelectrodes 151, 152, 153 and 154 are less than 10 degrees, theefficiency of reflection of light is lowered due to a very gentle slope.In addition, there is a problem in that the uniformity of thickness onthe surface of the lower electrode cannot be ensured due to a lowinclination angle. If the inclination angles (b) of the lower electrodes151, 152, 153 and 154 exceed 45 degrees, cracks may be produced in asubsequent layer due to a high inclination angle.

The adjustment of the inclination angles (b) of the lower electrodes151, 152, 153 and 154, which are defined with respect to the surface ofthe second semiconductor layer 130, can be achieved by means of changesin disposition of the substrate and the angle of the substrate withrespect to the advancing direction of metal atoms in a process such asthermal deposition.

In FIGS. 3 and 4 , the regions in which the four lower electrodes 151,152, 153 and 154 are formed define four cell regions 161, 162, 163 and164, respectively. The second semiconductor layer 130 is exposed inspaces among the cell regions 161, 162, 163 and 164. The number of thecell regions 161, 162, 163 and 164 may correspond to that of lightemitting diodes included in an array to be formed. Therefore, the numberof the cell regions may be variously changed.

Although FIG. 4 shows that the lower electrode 151, 152, 153 or 154 isdiscrete in the same cell region 161, 162, 163 or 164, this is becauseFIG. 4 shows the sectional view taken along line A1-A2 traversing thevia hole structures 140. As can be seen in FIG. 3 , the lower electrode151, 152, 153 or 154 formed in the same cell region is physicallycontinuous. Thus, the lower electrode 151, 152, 153 or 154 formed in thesame cell region is in an electrically short-circuited state even thoughthe via hole structures 140 are formed therein.

FIG. 5 is a plan view showing a state where cell regions are separatedwith respect to the structure of FIG. 3 , FIG. 6 is a sectional viewtaken along line A1-A2 in the plan view of FIG. 5 , and FIG. 7 is aperspective view of the structure in the plan view of FIG. 5 .

Referring to FIGS. 5, 6 and 7 , mesa-etched regions are formed throughmesa etching for the spaces among the four cell regions 161, 162, 163and 164. The substrate 100 is exposed in the mesa-etched regions formedthrough the mesa etching. Thus, the four cell regions 161, 162, 163 and164 are electrically completely separated from one another. If a bufferlayer is interposed between the substrate 100 and the firstsemiconductor layer 110 in FIGS. 1 to 4 , the buffer layer may remaineven in the separation process of the cell regions 161, 162, 163 and164. However, in order to completely separate the cell regions 161, 162,163 and 164 from one another, the buffer layer between adjacent ones ofthe cell regions 161, 162, 163 and 164 may be removed through the mesaetching.

Side surfaces of the first semiconductor layer 110, the active layer120, the second semiconductor layer 130 and the lower electrodes 151,152, 153 and 154 are exposed on side surfaces of the mesa regions bymeans of the mesa etching. The exposed side surfaces may haveinclination angles (c) of 10 to 60 degrees with respect to the surfaceof the substrate 100. The adjustment of the inclination angles (c) ofthe exposed side surfaces can be achieved by adjusting the angle of thesubstrate with respect to the advancing direction of an etchant.

If the inclination angles (c) of films exposed by means of the mesaetching are less than 10 degrees, a decrease in light-emitting area iscaused due to a low inclination angle, and light efficiency may belowered. If the inclination angle (c) exceeds 60 degrees, the thicknessof a film formed later may not be uniform or cracks may be produced inthe film due to a high inclination angle. This becomes a factor indeterioration of the reliability of a device.

The range of the inclination angles (c) of the films exposed through themesa etching has influence on the reflection of light caused by a metallayer formed in a subsequent process. For example, the metal layer isformed on sidewalls of the films exposed through the mesa etching. Ifthe inclination angle (c) is less than 10 degrees, light formed in theactive layer is not reflected in a predetermined range with respect tothe substrate but scattered. Even though the inclination angle (c)exceeds 60 degrees, the reflection of light is not progressed toward apredetermined region but scattered.

With the separation process between adjacent ones of the cell regions161, 162, 163 and 164, first semiconductor layers 111, 112, 113 and 114,active layers 121, 122, 123 and 124, second semiconductor layers 131,132, 133 and 134 and lower electrodes 151, 152, 153 and 154 areindependently formed in the cell regions 161, 162, 163 and 164,respectively. Thus, the first lower electrode 151 is exposed in thefirst cell region 161, and the first semiconductor layer 111 is exposedthrough the via hole structures 140. The second lower electrode 152 isexposed in the second cell region 162, and the first semiconductor layer112 is exposed through the via hole structures 140. Similarly, the thirdlower electrode 153 and the first semiconductor layer 113 are exposed inthe third cell region 163, and the fourth lower electrode 154 and thefirst semiconductor layer 114 are exposed in the fourth cell region 164.

In some implementations of the disclosed technology, the light emittingdiode refers to a structure in which the first semiconductor layer 111,112, 113 or 114, the active layer 121, 122, 123 or 124 and the secondsemiconductor layer 131, 132, 133 or 134 are laminated, respectively.Thus, one light emitting diode is formed in one cell region. When thelight emitting diode is modeled such that the first semiconductor layer111, 112, 113 or 114 has n-type conductivity and the secondsemiconductor layer 131, 132, 133 or 134 has p-type conductivity, thelower electrode 151, 152, 153 or 154 formed on the second semiconductorlayer 131, 132, 133 or 134 may be referred to as an anode electrode ofthe light emitting diode.

FIG. 8 is a plan view showing that a first interlayer insulating layeris formed on an entire surface of the structure of FIGS. 5 to 7 , andportions of a first semiconductor layer and the lower electrodes areexposed in each of the cell regions.

Moreover, FIGS. 9 to 12 are sectional views taken along specific linesin the plan view of FIG. 8 . Particularly, FIG. 9 is a sectional viewtaken along line B1-B2 in the plan view of FIG. 8 , FIG. 10 is asectional view taken along line C1-C2 in the plan view of FIG. 8 , FIG.11 is a sectional view taken along line D1-D2 in the plan view of FIG. 8, and FIG. 12 is a sectional view taken along line E1-E2 in the planview of FIG. 8 .

First, a first interlayer insulating layer 170 is formed with respect tothe structure of FIGS. 5 to 7 . Moreover, portions of the lowerelectrodes 151, 152, 153 and 154 and of the first semiconductor layers111, 112, 113 and 114 under the via hole structures are exposed by meansof patterning.

For example, in the first cell region 161, two pre-formed via holestructures are opened so that portions of the first semiconductor layer111 are exposed, and a portion of the first lower electrode 151 formedon the pre-formed second semiconductor layer 131 is exposed. In thesecond cell region 162, portions of the first semiconductor layer 112are exposed through the pre-formed via hole structures, and a portion ofthe second lower electrode 152 is exposed by means of etching for aportion of the first interlayer insulating layer 170. In the third cellregion 163, portions of the first semiconductor layer 113 are exposedthrough the via hole structures, and a portion of the third lowerelectrode 153 is exposed by means of etching for a portion of the firstinterlayer insulating layer 170. In the fourth cell region 164, portionsof the first semiconductor layer 114 are exposed through the via holestructures, and a portion of the fourth lower electrode 154 is exposedby means of etching for a portion of the first interlayer insulatinglayer 170.

As a result, in FIGS. 8 to 12 , the first interlayer insulating layer170 is formed on the entire surface of the substrate, and the portionsof the first semiconductor layers 111, 112, 113 and 114 under the viahole structures and the portions of the lower electrodes 151, 152, 153and 154 on the second semiconductor layers 131, 132, 133 and 134 areexposed in each of the cell regions 161, 162, 163 and 164 by means ofselective etching. The remaining region is shielded by the firstinterlayer insulating layer 170.

The first interlayer insulating layer 170 may be formed of or include aninsulating material having a light transmittance. For example, the firstinterlayer insulating layer may comprise SiO₂.

Furthermore, the first interlayer insulating layer 170 may have athickness of 2000 to 20000 Å.

If the thickness of the first interlayer insulating layer 170 is lessthan 2000 Å, it is difficult to secure an insulation property due to asmall thickness. In particular, if the first interlayer insulating layer170 is formed on the sidewalls of the mesa-etched regions or the viahole structures 140, the first interlayer insulating layer 170 has acertain slope, so that the insulation of the first interlayer insulatinglayer 170 may be broken down.

If the thickness of the first interlayer insulating layer 170 exceeds20000 Å, it is difficult to perform selective etching on the firstinterlayer insulating layer 170. For example, portions of the lowerelectrodes and the first semiconductor layer should be exposed in thevia hole structures 140. To this end, a process of applying the firstinterlayer insulating layer 170 to the entire surface and a selectiveetching process are performed. The application of a photoresist andpatterning are performed for the selective etching process. Etching isperformed for regions opened by a residual photoresist pattern. If thethickness of the first interlayer insulating layer 170 exceeds 20000 Å,the photoresist pattern to be used as an etching mask may also beremoved in the process of selectively etching the first interlayerinsulating layer 170. Therefore, the etching may be performed on anundesired portion, resulting in an error in the process.

The first interlayer insulating layer 170 may have an inclination angle(d) of 10 to 60 degrees with respect to the surface of the lowerelectrode exposed by the selective etching.

If the inclination angle d of the first interlayer insulating layer 170is less than 10 degrees, the area of the exposed surface of the lowerelectrode decreases or the substantial thickness of the first interlayerinsulating layer 170 decreases. Therefore, there is a problem in that itis difficult to secure an insulation property. That is, the firstinterlayer insulating layer 170 functions to electrically insulate thelower electrode from another conductive film formed thereon. Therefore,the first interlayer insulating layer 170 should have a sufficientthickness, and the lower electrode should be exposed with a certain areafor the purpose of additional electrical connection. If the firstinterlayer insulating layer 170 has a very low slope, the exposed areaof the lower electrode should be decreased to implement the firstinterlayer insulating layer 170 of a certain thickness. In a case whereit is intended to secure the area of the exposed lower electrode beyonda predetermined value, the insulation of the first interlayer insulatinglayer 170 with the small thickness may be broken down due to a lowslope.

If the inclination angle (d) of the first interlayer insulating layer170 exceeds 60 degrees, there is a problem in that the quality ofanother film to be formed on the first interlayer insulating layer 170may be deteriorated due to a large inclination angle.

The adjustment of the inclination angle of the first interlayerinsulating layer 170 can be achieved by adjusting the angle of etchingin a partial etching process for the first interlayer insulating layer170 formed on the lower electrode.

FIG. 13 is a plan view showing that upper electrodes are formed on thestructure illustrated in FIGS. 8 to 12 , and FIGS. 14 to 17 aresectional views taken along specific lines in the plan view of FIG. 13 .Particularly, FIG. 14 is a sectional view taken along line B1-B2 in theplan view of FIG. 13 , FIG. 15 is a sectional view taken along lineC1-C2 in the plan view of FIG. 13 , FIG. 16 is a sectional view takenalong line D1-D2 in the plan view of FIG. 13 , and FIG. 17 is asectional view taken along line E1-E2 in the plan view of FIG. 13 .

Referring to FIG. 13 , upper electrodes 181, 182, 183 and 184 areformed. The upper electrodes 181, 182, 183 and 184 are formed as fourdiscrete regions. For example, the first upper electrode 181 is formedover the first cell region 161 and a portion of the second cell region162. The second upper electrode 182 is formed over a portion of thesecond cell region 162 and a portion of the third cell region 163. Thethird upper electrode 183 is formed over a portion of the third cellregion 163 and a portion of the fourth cell region 164. The fourth upperelectrode 184 is formed in a portion of the fourth cell region 164.Thus, each of the upper electrodes 181, 182, 183 and 184 is formed whileshielding spaces between adjacent ones of the cell regions. The upperelectrodes 181, 182, 183 and 184 may cover no less than 30%, even noless than 50%, or no less than 90% of the spaces between the adjacentcell regions. However, since the upper electrodes 181, 182, 183 and 184are spaced apart from one another, the upper electrodes 181, 182, 183and 184 cover less than 100% of regions between adjacent ones of lightemitting diodes. The entire of the upper electrodes 181, 182, 183 and184 may occupy no less than 30%, even no less than 50%, or no less than90% of the entire area of the light emitting diode array. However, sincethe upper electrodes 181, 182, 183 and 184 are spaced apart from oneanother, they occupy less than 100% of the entire area of the lightemitting diode array. Each of the upper electrodes 181, 182, 183 and 184has the shape of a plate or sheet having a ratio of length and widthranging from 1:3 to 3:1. Further, at least one of the upper electrodes181, 182, 183 and 184 has a length or width greater than that of acorresponding light emitting diode (cell region).

Referring to FIG. 14 , the first upper electrode 181 is formed on thefirst interlayer insulating layer 170 in the first cell region 161, andis formed on portions of the first semiconductor layer 111 openedthrough the via hole structures. In addition, the first upper electrode181 allows a portion of the first lower electrode 151 to be exposed inthe first cell region 161 and is formed on a portion of the second lowerelectrode 152 exposed in the second cell region 162.

The second upper electrode 182 is formed on portions of the firstsemiconductor layer 112 exposed through the via hole structures in thesecond cell region 162 in a state in which the second upper electrode182 is physically separated from the first upper electrode 181. Inaddition, the second upper electrode 182 is formed on the firstinterlayer insulating layer 170.

In FIG. 14 , the first upper electrode 181 electrically connects thefirst semiconductor layer 111 in the first cell region 161 to the secondsemiconductor layer 132 in the second cell region 162. Despite of thepresence of the via hole structures, the second lower electrode 152 inthe second cell region 162 is entirely in an electricallyshort-circuited state in one cell region. Thus, the first semiconductorlayer 111 in the first cell region 161 is electrically connected to thesecond semiconductor layer 132 in the second cell region 162 through thesecond lower electrode 152.

In FIG. 15 , the second upper electrode 182 is formed on portions of thefirst semiconductor layer 112 exposed through the via hole structures inthe second cell region 162, and is formed to extend to the third lowerelectrode 153 in the third cell region 163.

The third upper electrode 183 physically separated from the second upperelectrode 182 is also formed on portions of the first semiconductorlayer 113 exposed through the via hole structures in the third cellregion 163.

In FIG. 15 , the second upper electrode 182 is electrically connected tothe portions of the first semiconductor layer 112 through the via holestructures in the second cell region 162, and is electrically connectedto the third lower electrode 153 in the third cell region 163. Thus, thefirst semiconductor layer 112 in the second cell region 162 can maintainthe same potential as the second semiconductor layer 133 in the thirdcell region 163.

Referring to FIG. 16 , the third upper electrode 183 is formed onportions of the first semiconductor layer 113 exposed through the viahole structures in the third cell region 163, and is formed to extend tothe fourth lower electrode 154 in the fourth cell region 164. Thus, thefirst semiconductor layer 113 in the third cell region 163 iselectrically connected to the second semiconductor layer 134 in thefourth cell region 164.

The fourth upper electrode 184 physically separated from the third upperelectrode 183 is electrically connected to the portions of the firstsemiconductor layer 114 exposed through the via hole structures in thefourth cell region 164.

Referring to FIG. 17 , the fourth upper electrode 184 is formed onportions of the first semiconductor layer 114 exposed through the viahole structures in the fourth cell region 164. The first upper electrode181 physically separated from the fourth upper electrode 184 is formedon portions of the first semiconductor layer 111 exposed through the viahole structures in the first cell region 161, and allows a portion ofthe first lower electrode 151 to be exposed in the first cell region161.

The contents disclosed in FIGS. 13 to 17 will be summarized below. Thefirst semiconductor layer 111 in the first cell region 161 and thesecond semiconductor layer 132 in the second cell region 162 establishthe same potential through the first upper electrode 181. The firstsemiconductor layer 112 in the second cell region 162 and the secondsemiconductor layer 133 in the third cell region 163 establish the samepotential through the second upper electrode 182. The firstsemiconductor layer 113 in the third cell region 163 establish the samepotential as the second semiconductor layer 134 in the fourth cellregion 164 through the third upper electrode 183. The first lowerelectrode 151 electrically connected to the second semiconductor layer131 in the first cell region 161 is exposed.

Of course, the same potential is established by assuming idealelectrical connection in a state where resistances of the upperelectrodes 181, 182, 183 and 184 and contact resistances between theupper electrodes 181, 182, 183 and 184 and the lower electrodes 151,152, 153 and 154 are neglected. Thus, in the operation of an actualdevice, a voltage drop may be sometimes caused by resistance componentsof the upper electrodes 181, 182, 183 and 184 and the lower electrodes151, 152, 153 and 154, which are kinds of metal wires.

The upper electrodes 181, 182, 183 and 184 may be formed of or includeany of materials that can be in ohmic contact with the firstsemiconductor layers 111, 112, 113 and 114. In addition, any materialmay be used for the upper electrodes 181, 182, 183 and 184 as long as itis a material that can be in ohmic contact with the lower electrodes151, 152, 153 and 154 made of or including a metallic material. Thus,the upper electrodes 181, 182, 183 and 184 may include, as an ohmiccontact layer, a metal layer comprising Ni, Cr, Ti, Rh or Al; or aconductive oxide layer such as an ITO layer.

The upper electrodes 181, 182, 183 and 184 may include a reflectivelayer including Al, Ag, Rh or Pt in order to reflect light, which isgenerated from the active layers 121, 122, 123 and 124 in the respectivecell regions 161, 162, 163 and 164, toward the substrate 100. Inparticular, the light generated from the respective active layers 121,122, 123 and 124 is reflected from the lower electrodes 151, 152, 153and 154 toward the substrate 100. In addition, light transmitted throughthe spaces between the adjacent ones of the cell regions 161, 162, 163and 164 is reflected by the upper electrodes 181, 182, 183 and 184shielding the spaces between the adjacent ones of the cell regions 161,162, 163 and 164.

The thicknesses of the upper electrodes 181, 182, 183 and 184 may be ina range of 2000 to 10000 Å. If the thicknesses of the upper electrode181, 182, 183 and 184 are less than 2000 Å, the reflection of the lightfrom the upper electrodes 181, 182, 183 and 184 toward the substrate 100is not smooth, and there is a leakage of light transmitted through theupper electrodes 181, 182, 183 and 184 in the form of thin films. If thethicknesses of the upper electrode 181, 182, 183 and 184 exceed 10000 Å,there is a problem in that it takes an excessive amount of time to formthe upper electrodes by means of thermal deposition or the like.

Further, the upper electrodes 181, 182, 183 and 184 may have inclinationangles (e) of 10 to 45 degrees with respect to the surface of the firstinterlayer insulating layer 170. If the inclination angles (e) of theupper electrodes 181, 182, 183 and 184 are less than 10 degrees, theefficiency of the reflection of light is lowered due to a very gentleslope. In addition, there is a problem in that the uniformity ofthickness on the surface of the upper electrode cannot be secured due toa small inclination angle. If the inclination angles (e) of the upperelectrodes 181, 182, 183 and 184 exceed 45 degrees, cracks may beproduced in a subsequent layer due to a large inclination angle.

The adjustment of the inclination angles (e) of the upper electrodes181, 182, 183 or 184, which are defined with respect to the surface ofthe first interlayer insulating layer 170, can be achieved by means ofchanges in disposition of the substrate and the angle of the substratewith respect to the advancing direction of metal atoms in a process suchas thermal deposition.

If the first semiconductor layers 111, 112, 113 and 114 have n-typeconductivity and the second semiconductor layers 131, 132, 133 and 134have p-type conductivity, each of the upper electrodes may be modeled asa cathode electrode of the light emitting diode, and simultaneously aswiring for connecting the cathode electrode of the light emitting diodeto the lower electrode that is an anode electrode of a light emittingdiode formed in an adjacent cell region. That is, in the light emittingdiode formed in the cell region, the upper electrode may be modeled toform a cathode electrode and simultaneously to be wiring forelectrically connecting the cathode electrode of the light emittingdiode to an anode electrode of a light emitting diode in an adjacentcell region.

FIG. 18 is a perspective view of the structure in the plan view of FIG.13 .

Referring to FIG. 18 , the first to third upper electrodes 181 to 183are formed over at least two cell regions. The space between adjacentcell regions is shielded. The upper electrodes allow light, which may beleaked between adjacent cell regions, to be reflected through thesubstrate, and are electrically connected to the first semiconductorlayer in each cell region. The upper electrodes are electricallyconnected to the second semiconductor layer in an adjacent cell region.

FIG. 19 is an equivalent circuit diagram obtained by modeling thestructure of FIGS. 13 to 18 according to an embodiment of the disclosedtechnology.

Referring to FIG. 19 , four light emitting diodes D1, D2, D3 and D4 anda wiring relationship among the light emitting diodes are shown.

The first light emitting diode D1 is formed in the first cell region161, the second light emitting diode D2 is formed in the second cellregion 162, the third light emitting diode D3 is formed in the thirdcell region 163, and the fourth light emitting diode D4 is formed in thefourth cell region 164. The first semiconductor layers 111, 112, 113 and114 in the cell regions 161, 162, 163 and 164 are modeled as n-typesemiconductors, and the second semiconductor layers 131, 132, 133 and134 are modeled as p-type semiconductors.

The first upper electrode 181 is electrically connected to the firstsemiconductor layer 111 in the first cell region 161 and extends to thesecond cell region 162 so as to be electrically connected to the secondsemiconductor layer 132 in the second cell region 162. Thus, the firstupper electrode 181 is modeled as wiring for connecting a cathodeterminal of the first light emitting diode D1 to an anode electrode ofthe second light emitting diode D2.

The second upper electrode 182 is modeled as wiring for connectionbetween a cathode terminal of the second light emitting diode D2 and ananode terminal of the third light emitting diode D3. The third upperelectrode 183 is modeled as wiring for connection between a cathodeelectrode of the third light emitting diode D3 and an anode terminal ofthe fourth light emitting diode D4. The fourth upper electrode 184 ismodeled as wiring for forming a cathode electrode of the fourth lightemitting diode D4.

Thus, the anode terminal of the first light emitting diode D1 and thecathode terminal of the fourth light emitting diode D4 are in anelectrically opened state with respect to an external power source, andthe other light emitting diodes D2 and D3 are electrically connected inseries. In order to perform a light-emitting operation, the anodeterminal of the first light emitting diode D1 should be connected to apositive power voltage V+, and the cathode terminal of the fourth lightemitting diode D4 should be connected to a negative power voltage V−.Thus, the light emitting diode connected to the positive power voltageV+ can be referred to as an input light emitting diode, and the lightemitting diode connected to the negative power voltage V− can bereferred to as an output light emitting diode.

In the connection relationships among the plurality of light emittingdiodes configured as described above, a cell region in which the cathodeterminal connected to the negative power voltage V− is formed isprovided with an upper electrode for shielding only a portion of thecorresponding cell region. A cell region in which another connectionrelationship is established is provided with an upper electrode formaking a shield between cell regions electrically connected to eachother.

FIG. 20 is a plan view showing that a second interlayer insulating layeris applied on an entire surface of the structure of FIG. 13 , a portionof the first electrode in the first cell region is exposed, and aportion of the fourth lower electrode in the fourth cell region isexposed.

Referring to FIG. 20 , with a second interlayer insulating layer 190,the upper electrodes are shielded, and a portion of the first lowerelectrode 151 and a portion of the fourth upper electrode 184 areexposed. This means that, in FIG. 19 , only the anode terminal of thefirst light emitting diode D1 is exposed and only the cathode terminalof the fourth light emitting diode D4 is exposed.

FIG. 21 is a sectional view taken along line B1-B2 in the plan view ofFIG. 20 , FIG. 22 is a sectional view taken along line C1-C2 in the planview of FIG. 20 , FIG. 23 is a sectional view taken along line D1-D2 inthe plan view of FIG. 20 , and FIG. 24 is a sectional view taken alongline E1-E2 in the plan view of FIG. 20 .

Referring to FIG. 21 , in the first cell region 161, portions of thefirst lower electrode 151 electrically connected to the secondsemiconductor layer 131 are opened. The remaining portions in the firstcell region are covered with the second interlayer insulating layer 190that is also over the second cell region 162.

Referring to FIG. 22 , the second and third cell regions 162 and 163 arecompletely covered with the second interlayer insulating layer 190.

Referring to FIGS. 23 and 24 , portions of the fourth upper electrode184 in the fourth cell region 164 are exposed, and portions of the firstlower electrode 151 in the first cell region 161 are exposed.

The exposure of the fourth upper electrode 184 and the first lowerelectrode 151 is performed by selective etching for the secondinterlayer insulating layer 190.

The second interlayer insulating layer 190 is selected from aninsulation material capable of protecting an underlying film from anexternal environment. In particular, the second interlayer insulatinglayer may comprise SiN or the like that has an insulation property andcan block a change in temperature or humidity.

The thickness of the second interlayer insulating layer 190 may be in apredetermined range. For example, if the second interlayer insulatinglayer 190 comprises SiN, the second interlayer insulating layer 190 mayhave a thickness of 2000 to 20000 Å.

If the thickness of the second interlayer insulating layer 190 is lessthan 2000 Å, it is difficult to secure an insulation property due to asmall thickness. In addition, there is a problem with protection of anunderlying layer against penetration of external moisture or chemicaldue to the small thickness.

If the thickness of the second interlayer insulating layer 190 exceeds20000 Å, it is difficult to perform selective etching on the secondinterlayer insulating layer 190 by means of formation of a photoresistpattern. That is, the photoresist pattern serves as an etching mask inthe etching process, and the photoresist pattern is also etched alongwith the selective etching of the second interlayer insulating layer 190due to the excessive thickness of the second interlayer insulating layer190. If the thickness of the second interlayer insulating layer 190 isexcessive, the photoresist pattern may be removed before the selectiveetching of the second interlayer insulating layer 190 is completed,resulting in a problem of etching performed at an undesired position.

The second interlayer insulating layer 190 may have an inclination angle(f) of 10 to 60 degrees with respect to the surface of the fourth upperelectrode 184 or first lower electrode 151 which is exposed therebelow.

If the inclination angle (f) of the second interlayer insulating layer190 is less than 10 degrees, the substantial area of the fourth upperelectrode 184 or first lower electrode 151 that has been exposeddecreases. If the area of the exposed portion is increased to secure thesubstantial area, there is a problem in that an insulation propertycannot be secured due to a small inclination angle.

If the inclination angle (f) of the second interlayer insulating layer190 exceeds 60 degrees, the quality of another layer to be formed on thesecond interlayer insulating layer 190 may be deteriorated due to asteep profile or slope, or cracks may be produced in the layer. Inaddition, in a light-emitting operation according to continuous supplyof power, properties of the light emitting diode are deteriorated.

FIG. 25 is a plan view showing that first and second pads are formed inthe structure of FIG. 20 .

Referring to FIG. 25 , the first pad 210 may be formed over the firstand second cell regions 161 and 162. Accordingly, the first pad 210 canbe electrically connected to the first lower electrode 151 in the firstcell region 161, which is exposed in FIG. 20 .

Moreover, the second pad 220 is formed to be spaced apart from the firstpad 210 at a predetermined distance, and may be formed over the thirdand fourth cell regions 163 and 164. The second pad 220 is electricallyconnected to the fourth upper electrode 184 in the fourth cell region164, which is exposed in FIG. 20 .

FIG. 26 is a sectional view taken along line B1-B2 in the plan view ofFIG. 25 , FIG. 27 is a sectional view taken along line C1-C2 in the planview of FIG. 25 , FIG. 28 is a sectional view taken along line D1-D2 inthe plan view of FIG. 25 , and FIG. 29 is a sectional view taken alongline E1-E2 in the plan view of FIG. 25 .

Referring to FIG. 26 , the first pad 210 is formed over the first andsecond cell regions 161 and 162. The first pad 210 is formed on thefirst lower electrode 151 exposed in the first cell region 161, and onthe second interlayer insulating layer 190 in the other cell regions.Thus, the first pad 210 is electrically connected to the secondsemiconductor layer 131 in the first cell region 161 through the firstlower electrode 151.

Referring to FIG. 27 , the first pad 210 is formed in the second cellregion 162, and the second pad 220 is formed to be spaced apart from thefirst pad 210 in the third cell region 163. The electrical contact ofthe first or second pad 210 or 220 with the lower or upper electrode isblocked in the second and third cell regions 162 and 163.

Referring to FIG. 28 , the second pad 220 is formed over the third andfourth cell regions 163 and 164. In some implementations, the second pad220 is electrically connected to the fourth upper electrode 184 openedin the fourth cell region 164. Thus, the second pad 220 is electricallyconnected to the first semiconductor layer 114 in the fourth cell region164.

Referring to FIG. 29 , the second pad 220 is formed in the fourth cellregion 164, and the first pad 210 is formed to be spaced apart from thesecond pad 220 in the first cell region 161. The first pad 210 is formedon the first lower electrode 151 in the first cell region 161 andelectrically connected to the second semiconductor layer 131.

FIG. 30 is a perspective view taken along line C2-C3 in the plan view ofFIG. 25 .

Referring to FIG. 30 , the first semiconductor layer 113 in the thirdcell region 163 is electrically connected to the third upper electrode183. The third upper electrode 183 shields the space between the thirdand fourth cell regions 163 and 164 and is electrically connected to thefourth lower electrode 154 in the fourth cell region 164. The first andsecond pads 210 and 220 are spaced apart from each other and formed onthe second interlayer insulating layer 190. Of course, as describedabove, the first pad 210 is electrically connected to the secondsemiconductor layer 131 in the first cell region 161, and the second pad220 is electrically connected to the first semiconductor layer 111 inthe fourth cell region 164.

Each of the first and second pads 210 and 220 may have a first layercomprising Ti, Cr or Ni and a second layer comprising Al, Cu, Ag or Auformed thereon. The first and second pads 210 and 220 may be formedusing a lift-off process. They may be formed by forming a double- orsingle-layered metal film, forming a pattern through a conventionalphotolithography process, and then performing dry or wet etching usingthe pattern as an etching mask. However, an etchant used in the dry orwet etching may vary depending on the material of metal to be etched.

Accordingly, the first and second pads 210 and 220 can be simultaneouslyformed in one process.

A pad barrier layer (not shown) made of or including a conductivematerial may be formed on the first pad 210 or second pad 220. The padbarrier layer is provided to prevent diffusion of metal, which may occurin a bonding or soldering process for the pads 210 and 220. For example,in the bonding or soldering process, tin atoms contained in a bondingmetal or soldering material are diffused into the pads 210 and 220,thereby preventing an increase in resistivity of the pads. To this end,the pad barrier layer may be configured with a layer of Cr, Ni, Ti, W,TiW, Mo, or Pt or a composite thereof.

Referring to the modeling of FIG. 19 , the first semiconductor layers111, 112, 113 and 114 in the respective cell regions are modeled asn-type semiconductors, and the second semiconductor layers 131, 132, 133and 134 in the respective cell regions are modeled as p-typesemiconductors. The first lower electrode 151 formed on the secondsemiconductor layer 131 in the first cell region 161 is modeled as theanode electrode of the first light emitting diode D1. Thus, the firstpad 210 can be modeled as wiring connected to the anode electrode of thefirst light emitting diode D1. The fourth upper electrode 184electrically connected to the first semiconductor layer 114 in thefourth cell region 164 is modeled as the cathode electrode of the fourthlight emitting diode D4. Thus, the second pad 220 can be modeled aswiring connected to the cathode electrode of the fourth light emittingdiode D4.

Accordingly, an array structure in which the four light emitting diodesD1 to D4 are connected in series formed, and electrical connectionthereof to the outside is achieved through the two pads 210 and 220formed on the single substrate 100.

Referring to FIG. 19 , the first lower electrode 152 of the first lightemitting diode D1 connected to the positive power voltage V+ iselectrically connected to the first pad 210, and the fourth upperelectrode 184 of the fourth light emitting diode D4 connected to thenegative power voltage V− is electrically connected to the second pad220.

In some implementations of the disclosed technology, there is shown thatfour light emitting diodes are formed while being separated from oneanother and an anode terminal of one of the light emitting diodes iselectrically connected to a cathode terminal of another of the lightemitting diodes through the lower and upper electrodes. However, thefour light emitting diodes in this embodiment are merely an example, andvarious numbers of light emitting diodes may be formed.

FIG. 31 is a circuit diagram obtained by modeling a connection of tenlight emitting diodes in series according to an embodiment of thedisclosed technology.

Referring to FIG. 31 , ten cell regions 301 to 310 are defined using theprocess shown in FIG. 5 . A first semiconductor layer, an active layer,a second semiconductor layer and a lower electrode in each of the cellregions 301 to 310 are separated from those in other cell regions. Therespective lower electrodes are formed on the second semiconductorlayers so as to form anode electrodes of light emitting diodes D1 toD10.

Subsequently, a first interlayer insulating layer and upper electrodesare formed using the processes shown in FIGS. 6 to 17 . The formed upperelectrodes shield the space between adjacent cell regions, and serve aswiring for achieving electrical connection between anode electrodes ofadjacent light emitting diodes.

Furthermore, a second interlayer insulating layer is formed using theprocesses shown in FIGS. 20 to 29 . The lower electrode of the firstlight emitting diode D1 that is the input light emitting diode connectedto a positive power voltage V+ on a current path is exposed, and theupper electrode of the tenth light emitting diode D10 that is an outputlight emitting diode connected to a negative power voltage V− on thecurrent path is opened. Then, a first pad 320 is formed and connected tothe anode terminal of the first light emitting diode D1, and a secondpad 330 is formed and connected to a cathode terminal of the tenth lightemitting diode D10.

The other light emitting diodes are connected in series or parallel soas to form an array.

FIG. 32 is a circuit diagram obtained by modeling an array having lightemitting diodes connected in series or parallel according to anembodiment of the disclosed technology.

Referring to FIG. 32 , a plurality of light emitting diodes D1 to D8 areconnected in series and/or in parallel to one another. The lightemitting diodes D1 to D8 are formed independently of one another throughthe definitions of cell regions 401 to 408. As described above, an anodeelectrode of each of the light emitting diode D1 to D8 is formed througha lower electrode. Wiring between a cathode electrode of each of thelight emitting diodes D1 to D8 and the anode electrode of an adjacentlight emitting diode is made by forming an upper electrode andperforming an appropriate wiring process. However, the lower electrodeis formed on a second semiconductor layer, and the upper electrode isformed to shield the space between adjacent cell regions.

Finally, a first pad 410 supplied with a positive power voltage V+ iselectrically connected to the lower electrode formed on the secondsemiconductor layer of the first or third light emitting diode D1 or D3,and a second pad 420 supplied with a negative power voltage V− iselectrically connected to the upper electrode that is a cathodeelectrode of the sixth or eighth light emitting diode D6 or D8.

Thus, in FIG. 32 , the input light emitting diode corresponds to thefirst and third light emitting diodes D1 and D3, and the output lightemitting diode corresponds to the sixth and eighth light emitting diodesD6 and D8.

According to some implementations of the disclosed technology describedabove, light generated in the active layer of each of the light emittingdiodes is reflected from the lower and upper electrodes toward thesubstrate, and the flip-chip type light emitting diodes are electricallyconnected through wiring of the upper electrodes on a single substrate.The upper electrode is shielded from the outside through the secondinterlayer insulating layer. The first pad supplied with a positivepower voltage is electrically connected to a lower electrode of a lightemitting diode connected most closely to the positive power voltage. Thesecond pad supplied with a negative power voltage is electricallyconnected to an upper electrode of a light emitting diode connected mostclosely to the negative power voltage.

Thus, it is possible to solve inconvenience in a process of mounting aplurality of flip-chip type light emitting diodes on a submountsubstrate and implementing two terminals to an external power sourcethrough wiring arranged on the submount substrate. In addition, thespace between adjacent cell regions can be shielded by the upperelectrode, thereby maximizing the reflection of light toward thesubstrate.

Further, the second interlayer insulating layer protects a laminatedstructure, which is arranged between the substrate and the secondinterlayer insulating layer, from external temperature or humidity andthe like. Thus, it is possible to implement a structure that can bedirectly mounted on a substrate without intervention of any separatepackaging means.

In particular, since a plurality of flip-chip type light emitting diodesare implemented on a single substrate, there is an advantage in that acommercial power source can be directly used while excluding a voltagedrop, a conversion of voltage level or a conversion of waveform for thecommercial power source.

FIGS. 33 and 34 are a plan view and a sectional view showing that firstvia hole structures are formed in a plurality of laminated structuresaccording to an embodiment of the present disclosure.

In particular, FIG. 34 is a sectional view taken along line A1-A2 in theplan view of FIG. 33 .

Referring to FIGS. 33 and 34 , the first semiconductor layer 110, theactive layer 120 and the second semiconductor layer 130 are formed onthe substrate 100, and a first via hole structures 140 a are formed toallow the surface of the first semiconductor layer 110 to be exposedtherethrough.

The substrate 100 may comprise a material such as sapphire, siliconcarbide or GaN. Any material may be used for the substrate 100 as longas it can induce the growth of the thin film. The first semiconductorlayer 110 may have the n-type conductivity. Further, the active layer120 may have a multiple quantum well structure, and the secondsemiconductor layer 130 is formed on the active layer 120. When thefirst semiconductor layer 110 has the n-type conductivity, the secondsemiconductor layer 130 has the p-type conductivity. Further, the bufferlayer (not shown) may be further formed between the substrate 100 andthe first semiconductor layer 110 so as to facilitate the singlecrystalline growth of the first semiconductor layer 110.

Subsequently, the selective etching is performed on the structure formedwith the second semiconductor layer 130 and the plurality of first viahole structures 140 a are formed. Portions of the lower firstsemiconductor layer 110 are exposed through the first via holestructures 140 a. The first via hole structures 140 a may be formed bythe conventional etching process. For example, the photoresist isapplied, and portions of the photoresist on the regions where the firstvia hole structures will be formed are then removed by the conventionalpatterning process to form a photoresist pattern. Thereafter, theetching process is performed by using the photoresist pattern as theetching mask. The etching process is performed until the portions of thefirst semiconductor layer 110 are exposed. After the etching process,the photoresist pattern remaining is removed.

According to the embodiment of the present disclosure, the first viahole structures 140 a may have a dumbbell shape which is parallel withone side of the substrate 100, the first semiconductor layer 110, theactive layer 120, or the second semiconductor layer 130 and has alength. In some implementations, the first via hole structures 140 a mayinclude a pair of via holes disposed at or around distal ends of thecorresponding light emitting diodes so as to be formed at both sides ofthe first via hole structures 140 a, and connection parts connectingbetween the pair of via hole structures.

Referring back to FIG. 33 , the first via hole structures 140 a may bedisposed in parallel with one side, for example, horizontal side, of therectangular second semiconductor layer 130. In some implementations, thesecond semiconductor layer 130 may have a shape with a long horizontalside and a short vertical side and a length of the first via holes 140 amay be proportional to a length of the long horizontal side of thesecond semiconductor layer 130.

The shape of the first via hole structures 140 a is not limited theretoand the shape and the number of first via hole structures 140 a may bevariously changed. The shapes and the effects of the first via holestructures 140 a will be described in detail below.

FIGS. 35 and 36 are a plan view and a sectional view showing that lowerelectrodes are formed on a second semiconductor layer of FIG. 33 , inparticular, FIG. 36 is a sectional view taken along line A1-A2 in theplan view of FIG. 35 .

Referring to FIGS. 35 and 36 , the lower electrodes 151, 152, 153 and154 are disposed to be formed in the regions except the first via holestructures 140 a, and the plurality of cell regions 161, 162, 163 and164 may be defined by the formation of the lower electrodes 151, 152,153 and 154. Further, The lower electrodes 151, 152, 153 and 154 may beformed by employing the lift-off process used upon formation of a metalelectrode. For example, the photoresist is formed in the separatingregions excluding the virtual cell regions 161, 162, 163 and 164 and inthe regions in which the first via hole structures 140 a are formed, andthe metal layer is formed by conventional thermal deposition or thelike. Subsequently, the photoresist is removed, thereby forming thelower electrodes 151, 152, 153 and 154 on the second semiconductor layer130. Any material may be employed for the lower electrodes 151, 152, 153and 154 as long as it includes a metallic material capable of being inohmic contact with the second semiconductor layer 130. Further, thelower electrodes 151, 152, 153 and 154 may comprise the reflective layermade of or including Al, Ag, Rh, or Pt. For example, the lowerelectrodes 151, 152, 153, and 154 may comprise Ni, Cr or Ti, and may becomposed of or include a composite metal layer including, for example,Ti/Al/Ni/Au or a composite metal layer including Ni/Ag/Ni/Au.

In FIGS. 35 and 36 , the regions in which the four lower electrodes 151,152, 153 and 154 are formed define the four cell regions 161, 162, 163and 164, respectively. The second semiconductor layer 130 is exposed inthe spaces among the cell regions 161, 162, 163 and 164. The number ofthe cell regions 161, 162, 163 and 164 may correspond to that of lightemitting diodes included in the array to be formed. Therefore, thenumber of the cell regions 161, 162, 163 and 164 may be variouslychanged.

Further, although FIG. 36 shows that the lower electrodes 151, 152, 153and 154 are discrete in the same cell regions 161, 162, 163 and 164,this is because FIG. 36 shows the sectional view taken along line A1-A2of FIG. 35 , which traverses the first via hole structures 140 a. As canbe seen in FIG. 35 , the lower electrodes 151, 152, 153, and 154 formedin the same cell regions 161, 162, 163 and 164 are in the physicallyconnected state. Thus, the lower electrodes 151, 152, 153, and 154formed in the same cell regions 161, 162, 163, and 164 are in theelectrically short-circuited state even though the first via holestructures 140 a are formed therein.

FIG. 37 is a plan view showing a state of the structure of FIG. 35 wherecell regions are separated from one another, FIG. 38 is a sectional viewtaken along line A1-A2 in the plan view of FIG. 37 , and FIG. 39 is aperspective view of the structure of FIG. 37 .

Referring to FIGS. 37 to 39 , the mesa-etched regions are formed throughthe mesa etching on the spaces among the four cell regions 161, 162, 163and 164. The substrate 100 is exposed in the mesa-etched regions formedthrough the mesa etching. Thus, the four cell regions 161, 162, 163 and164 are electrically completely separated from one another. If thebuffer layer is interposed between the substrate 100 and the firstsemiconductor layer 110 in FIGS. 33 to 36 , the buffer layer may remaineven in the separation process of the cell regions 161, 162, 163 and164. However, in order to completely separate the cell regions 161, 162,163 and 164 from one another, the buffer layer between adjacent ones ofthe cell regions 161, 162, 163 and 164 may be removed through the mesaetching.

With the separation process between adjacent ones of the cell regions161, 162, 163 and 164, the first semiconductor layer 111, 112, 113 or114, the active layer 121, 122, 123 or 124, the second semiconductorlayer 131, 132, 133 or 134, and the lower electrode 151, 152, 153 or 154are independently formed in each of the cell regions 161, 162, 163 and164. Thus, the first lower electrode 151 is exposed in the first cellregion 161, and the first semiconductor layer 111 is exposed through thefirst via hole structures 140 a. Further, the second lower electrode 152is exposed in the second cell region 162, and the first semiconductorlayer 112 is exposed through the first via hole structures 140 a.Similarly, the third lower electrode 153 and the first semiconductorlayer 113 are exposed in the third cell region 163, and the fourth lowerelectrode 154 and the first semiconductor layer 114 are exposed in thefourth cell region 164.

Further, in the present disclosure, the light emitting diode has astructure in which the first semiconductor layer 111, 112, 113 or 114,the active layer 121, 122, 123 or 124 and the second semiconductor layer131, 132, 133 or 134 are laminated, respectively. Thus, one lightemitting diode is formed in one cell region. Further, when the lightemitting diode is configured such that the first semiconductor layer111, 112, 113 or 114 has the n-type conductivity and the secondsemiconductor layer 131, 132, 133 or 134 has the p-type conductivity,the lower electrode 151, 152, 153 or 154 formed on the secondsemiconductor layer 131, 132, 133 or 134 may be referred to as an anodeelectrode of the light emitting diode.

Further, in the present disclosure, each of the light emitting diodesmay include one first via hole structures 140 a through which the firstsemiconductor layers 111, 112, 113, and 114 are exposed. The first viahole structures 140 a may have a length proportional to a length of oneside of the second semiconductor layers 131, 132, 133, and 134 in thelight emitting diode in which the first via hole structures 140 a isdisposed. The first via hole structures 140 a may have a length rangingfrom no less than 30% to less than 100% of the length of the long sideof the second semiconductor layer. When the length of the first via holestructure 140 a is less than 30% of the length of one side of the secondsemiconductor layer, it may be difficult to effectively diffuse acurrent.

Referring back to FIG. 37 , when the second semiconductor layer 131,132, 133, or 134 has a generally rectangular shape, the length of oneside means the length of the horizontal side or the length of thevertical side of the, second semiconductor layer. In the presentembodiment, the length of one side means the length of the horizontalside of the second semiconductor layer but other implementations arealso possible. Since the length of the first via hole structures 140 ais proportional to the length of one side of the second semiconductorlayers 131, 132, 133, and 134, an area of the first via hole structures140 a may be constantly increased as an area of the second semiconductorlayers 131, 132, 133, and 134 is constantly increased. By doing so, thearea of the exposed first semiconductor layers 111, 112, 113, and 114may also be increased. The first via hole structures 140 a may have adumbbell shape, a rectangular shape, or a rectangular shape of which thecorners are round, but is not limited thereto.

The first via hole structures 140 a may be disposed in parallel with oneside of the second semiconductor layer 131, 132, 133, or 134. Forexample, the dumbbell-shaped first via hole structures 140 a may bedisposed in parallel with one side of the second semiconductor layer131, 132, 133, or 134.

The first via hole structures 140 a may be disposed in a central regionof the second semiconductor layer 131, 132, 133, or 134. Further, atleast some of the first via hole structures 140 a may be disposed in thecentral region of the second semiconductor layer 131, 132, 133, or 134.By doing so, it is possible to easily diffuse the current of the lightemitting diode.

FIG. 40 is a plan view showing that the first interlayer insulatinglayer is formed on an entire surface of the structure of FIGS. 37 to 39, and portions of the first semiconductor layer and the lower electrodesare exposed in each of the cell regions.

Further, FIGS. 41 to 44 are sectional views taken along specific linesin the plan view of FIG. 40 . In particular, FIG. 41 is a sectional viewtaken along line B1-B2 in the plan view of FIG. 40 , FIG. 42 is asectional view taken along line C1-C2 in the plan view of FIG. 40 , FIG.43 is a sectional view taken along line D1-D2 in the plan view of FIG.40 , and FIG. 44 is a sectional view taken along line E1-E2 in the planview of FIG. 40 .

First, the first interlayer insulating layer 170 is formed over thestructure of FIGS. 37 to 39 . Moreover, portions of the lower electrodes151, 152, 153 and 154 and of the first semiconductor layers 111, 112,113 and 114 under the first via hole structures are exposed bypatterning.

For example, in the first cell region 161, the first via hole structuresare opened so that the portions of the first semiconductor layer 111 areexposed, and a portion of the first lower electrode 151 formed on thesecond semiconductor layer 131 is exposed through second via holestructures 151 h.

The second via hole structures 151 h may be disposed at both sides ofthe first via hole structures. At least two of the second via holestructures 151 h may be disposed to be spaced apart from the first viahole structures at a predetermined distance. For example, when viewingthe first cell region 161 from the top, two of the second via holestructures 151 h may be disposed to be vertically symmetrical in thefirst cell region. In some implementations, the second via holestructures 151 h may be disposed apart by a predetermined distance fromone distal end of the first via hole structures. As described above, thefirst via hole structures may be formed to include the pair of via holesdisposed at distal ends of the first via hole structures and theconnection parts connecting between the pair of via holes and one of thepair of via holes may be disposed apart by a predetermined distance fromthe four second via hole structures 151 h as illustrated in FIG. 40 .

In the present disclosure, the lower electrodes 151 exposed through thesecond via hole structures 151 h may be electrically connected to theoutside through the first pad later. The second via hole structures andthe first via hole structures keep a regularly spaced state at apredetermined distance from each other and therefore it is possible toeasily diffuse a current in the light emitting diode. Further, thesecond via hole structures may be disposed in a regular form with acolumn and row in consideration of the underlying first via holestructures and therefore the flow of current in the light emitting diodemay be uniform.

In the second cell region 162, the first semiconductor layer 112 exposedthrough the first via hole structures is exposed and a portion of thesecond lower electrode 152 is exposed by etching a portion of the firstinterlayer insulating layer 170.

In the third cell region 163, the first semiconductor layer 113 isexposed through the first via hole structures and a portion of the thirdlower electrode 153 is exposed by etching a portion of the firstinterlayer insulating layer 170.

In the fourth cell region 164, the first semiconductor layer 114 isexposed through the first via hole structures and a portion of thefourth lower electrode 154 is exposed by etching a portion of the firstinterlayer insulating layer 170.

As a result, in FIGS. 40 to 44 , the first interlayer insulating layer170 is formed on the entire surface of the substrate, and the portionsof the first semiconductor layers 111, 112, 113 and 114 under the firstvia hole structures and the portions of the lower electrodes 151, 152,153 and 154 on the second semiconductor layers 131, 132, 133 and 134 areexposed in each of the cell regions 161, 162, 163 and 164 by means ofthe selective etching. That is, the first semiconductor layers 111, 112,113, and 114 exposed through the first via hole structures pre-formed inthe previous step are exposed in each of the cell regions 161, 162, 163,and 164 and the portions of the lower electrodes 151, 152, 153, and 154are also exposed in each of the cell regions 161, 162, 163, and 164. Inthe case of the first cell region 161, the first interlayer insulatinglayer 170 has the second via hole structures 151 h and a portion of thelower electrode 151 is exposed through the second via hole structures151 h. The remaining region is shielded by the first interlayerinsulating layer 170.

The first interlayer insulating layer 170 may be formed of or include aninsulating material having predetermined light transmittance. Forexample, the first interlayer insulating layer 170 may comprise SiO₂. Insome implementations, the first interlayer insulating layer 170 may beformed of or include a distributed Bragg reflector in which materiallayers having different refractive indexes are laminated. For example,SiO₂/TiO₂ are repeatedly laminated to form the first interlayerinsulating layer 170, thereby reflecting light generated from the activelayer.

FIG. 45 is a plan view showing that the upper electrodes are formed onthe structure illustrated in FIGS. 40 to 44 . Further, FIGS. 46 to 49are sectional views taken along specific lines in the plan view of FIG.45 . In particular, FIG. 46 is a sectional view taken along line B1-B2in the plan view of FIG. 45 , FIG. 47 is a sectional view taken alongline C1-C2 in the plan view of FIG. 45 , FIG. 48 is a sectional viewtaken along line D1-D2 in the plan view of FIG. 45 , and FIG. 49 is asectional view taken along line E1-E2 in the plan view of FIG. 45 .

Referring to FIG. 45 , the upper electrodes 181, 182, 183, and 184 areformed. The upper electrodes 181, 182, 183, and 184 are formed as fourdiscrete regions. For example, the first upper electrode 181 is formedover the first cell region 161 and a portion of the second cell region162. Further, the second upper electrode 182 is formed over a portion ofthe second cell region 162 and a portion of the third cell region 163.The third upper electrode 183 is formed over a portion of the third cellregion 163 and a portion of the fourth cell region 164 and the fourthupper electrode 184 is formed in a portion of the fourth cell region164. Thus, each of the upper electrodes 181, 182, 183 and 184 is formedwhile shielding spaces between adjacent cell regions. The upperelectrodes 181, 182, 183 and 184 may cover no less than 30%, even noless than 50%, or no less than 90% of the spaces between the adjacentcell regions. However, since the upper electrodes 181, 182, 183 and 184are spaced apart from one another, the upper electrodes 181, 182, 183and 184 cover less than 100% of regions between adjacent light emittingdiodes.

The entire of the upper electrodes 181, 182, 183 and 184 may occupy noless than 30%, no less than 50%, no less than 70%, no less than 80%, orno less than 90% of the entire area of the light emitting diode array.However, since the upper electrodes 181, 182, 183 and 184 are spacedapart from one another, they occupy less than 100% of the entire area ofthe light emitting diode array. Further, the upper electrodes 181, 182,183, and 184 may have a plate or sheet shape. Further, at least one ofthe upper electrodes 181, 182, 183 and 184 may have a length or widthgreater than that of a corresponding light emitting diode (cell region).

Referring to FIG. 46 , the first upper electrode 181 is formed on thefirst interlayer insulating layer 170 in the first cell region 161, andis formed on the first semiconductor layer 111 opened through the firstvia hole structures. In addition, the first upper electrode 181 allows aportion of the first lower electrode 151 in the first cell region 161 tobe exposed through the second via hole structures and is formed on thesecond lower electrode 152 exposed in the second cell region 162.

Further, the second upper electrode 182 is formed on the firstsemiconductor layer 112 exposed through the first via hole structures inthe second cell region 162 in a state in which is the second upperelectrode 182 is physically separated from the first upper electrode 181and is formed on the first interlayer insulating layer 170 in theremaining region.

Referring back to FIG. 46 , the first upper electrode 181 electricallyconnects the first semiconductor layer 111 in the first cell region 161to the second semiconductor layer 132 in the second cell region 162.Despite the presence of the first via hole structures, the second lowerelectrode 152 in the second cell region 162 is in an electricallyshort-circuited state in one cell region. Thus, the first semiconductorlayer 111 in the first cell region 161 is electrically connected to thesecond semiconductor layer 132 in the second cell region 162 through thesecond lower electrode 152.

In FIG. 47 , the second upper electrode 182 is formed on the firstsemiconductor layer 112 exposed through the first via hole structures inthe second cell region 162, and is formed to extend to the third lowerelectrode 153 in the third cell region 163. Further, the third upperelectrode 183 physically separated from the second upper electrode 182is also formed on the first semiconductor layer 113 exposed through thefirst via hole structures in the third cell region 163.

In FIG. 47 , the second upper electrode 182 is electrically connected tothe first semiconductor layer 112 exposed through the first via holestructures in the second cell region 162, and is electrically connectedto the third lower electrode 153 in the third cell region 163. Thus, thefirst semiconductor layer 112 in the second cell region 162 can maintainthe same potential as the second semiconductor layer 133 in the thirdcell region 163.

Referring to FIG. 48 , the third upper electrode 183 is formed on thefirst semiconductor layer 113 exposed through the first via holestructures in the third cell region 163, and is formed to extend to thefourth lower electrode 154 in the fourth cell region 164. Thus, thefirst semiconductor layer 113 in the third cell region 163 iselectrically connected to the second semiconductor layer 134 in thefourth cell region 164. Further, the fourth upper electrode 184physically separated from the third upper electrode 183 is electricallyconnected to the first semiconductor layer 114 exposed through the firstvia hole structures in the fourth cell region 164.

Referring to FIG. 49 , the fourth upper electrode 184 is formed on thefirst semiconductor layer 114 exposed through the first via holestructures in the fourth cell region 164. Further, the first upperelectrode 181 physically separated from the fourth upper electrode 184is formed on the first semiconductor layer 111 exposed through the firstvia hole structures in the first cell region 161, and allows a portionof the first lower electrode 151 to be exposed in the first cell region161.

As discussed above, the first semiconductor layer 111 in the first cellregion 161 and the second semiconductor layer 132 in the second cellregion 162 establish the same potential through the first upperelectrode 181. Further, the first semiconductor layer 112 in the secondcell region 162 and the second semiconductor layer 133 in the third cellregion 163 establish the same potential through the second upperelectrode 182. The first semiconductor layer 113 in the third cellregion 163 establishes the same potential as the second semiconductorlayer 134 in the fourth cell region 164 through the third upperelectrode 183. The first lower electrode 151 electrically connected tothe second semiconductor layer 131 in the first cell region 161 isexposed.

The upper electrodes 181, 182, and 183 are electrically connected to thefirst semiconductor layers 111, 112, and 113 through the first via holestructures and establish the same potential as the second semiconductorlayers 132, 133, and 134. Thus, the first via hole structures accordingto the present embodiment have the dumbbell shape or the rectangularshape of which the corners are round. Compared with the case where theshape of a via hole structure is a circle, a contact area between thefirst semiconductor layer and the upper electrode through the first viahole is relatively wide.

The first via hole structures according to the present embodiment mayinclude two via holes disposed at the distal ends of the first via holestructures and the connection parts connecting between the via holes.Thus, as compared with the case where two via holes are simply disposedwithout the connection parts, the contact area between the firstsemiconductor layer and the upper electrode through the first via holestructures may be sufficiently secured. Further, a stress around thecontact area is reduced and thus a delamination phenomenon between thefirst semiconductor layer and the upper electrode may be reduced.Therefore, the reliability of the light emitting diode array accordingto the embodiment of the present disclosure may be improved.

Further, the area of the first via hole structures is proportional tothat of the second semiconductor layer and the length of the first viahole structures is proportional to that of the second semiconductorlayer. Thus, the first semiconductor layer having a proper area forefficiently diffusing a current may be exposed. Therefore, the lightemitting diode array according to the embodiment of the presentdisclosure can facilitate the current diffusion between the lightemitting diodes.

The establishing of the same potential is based on the assumption of anideal electrical connection where resistances of the upper electrodes181, 182, 183 and 184 and contact resistances between the upperelectrodes 181, 182, 183 and 184 and the lower electrodes 151, 152, 153and 154 are neglected. Thus, in the actual operation of a device, avoltage drop may occur due to resistance components of the upperelectrodes 181, 182, 183 and 184 and the lower electrodes 151, 152, 153and 154 that may include metal wires.

The upper electrodes 181, 182, 183 and 184 may comprise a reflectiveconductive layer 180 b. The reflective conductive layer 180 b mayinclude Al, Ag, Rh or Pt or a combination thereof. The upper electrodes181, 182, 183 and 184 including the reflective conductive layer 180 bmay reflect light which is generated from the active layers 121, 122,123 and 124 in the respective cell regions 161, 162, 163 and 164 towardthe substrate 100. Further, the upper electrodes 181, 182, 183, and 184may configure an omni-directional reflector together with the firstinterlayer insulating layer 170. Meanwhile, even when the firstinterlayer insulating layer 170 is formed of or includes the distributedBragg reflector, the upper electrodes 181, 182, 183, and 184 maycomprise the reflective conductive layer 180 b to improve lightreflectivity.

The upper electrodes 181, 182, 183 and 184 may further comprise theohmic contact layer 180 a beneath the reflective conductive layer 180 b.The ohmic contact layer 180 a may include, for example, Ni, Cr, Ti, Rh,or Al or a combination thereof as a material forming the ohmic contactbetween the first semiconductor layers 111, 112, 113, and 114 and thelower electrodes 151, 152, 153, and 154. However, the ohmic contactlayer 180 a is not limited thereto and any material may be used for thesubstrate 100 as long as it may also provide the ohmic-contact with thelower electrodes 151, 152, 153, and 154 of metallic materials whileforming the ohmic contact with the first semiconductor layers 111, 112,113, and 114. For example, a conductive oxide layer like ITO may beused.

The light generated from the active layers 121, 122, 123 and 124 in therespective cell regions 161, 162, 163, and 164 may be reflected from thelower electrodes 151, 152, 153 and 154 toward the substrate 100. Lighttransmitted through the spaces between the adjacent ones of the cellregions 161, 162, 163 and 164 is reflected by the first interlayerinsulating layer 170 and/or the upper electrodes 181, 182, 183 and 184shielding the spaces between the adjacent ones of the cell regions 161,162, 163 and 164. Light L which is generated from the active layers 121,122, 123, and 124 and proceeds toward the first via hole structures orthe spaces between the adjacent ones of the cell regions 161, 162, 163,and 164 may be reflected from the upper electrodes 181, 182, 183, and184 which include the first interlayer insulating layer 170 and/or thereflective conductive layer 180 b disposed on the side wall of the firstvia hole structures or the side walls of the spaces and may then beextracted to the outside through the substrate 100. Therefore, the lightloss may be reduced and thus the light extraction efficiency may beimproved.

In some implementations, the upper electrodes 181, 182, 183, and 184occupy a wide area of the light emitting diode array. For example, theupper electrodes 181, 182, 183, and 184 may cover no less than 70%, noless than 80%, or even no less than 90% of the entire area of the lightemitting diode array. Further, the interval between adjacent ones of theupper electrodes 181, 182, 183, and 184 may range from about 1 μm to 100μm. In some implementations, the interval between adjacent ones of theupper electrodes 181, 182, 183, and 184 may range from 5 μm to 15 μm.Therefore, it is possible to prevent light leakage in the first via holestructures or the spaces between adjacent ones of the cell regions 161,162, 163, and 164.

The upper electrodes 181, 182, 183 and 184 may further comprise abarrier layer 180 c disposed on the reflective conductive layer 180 b.The barrier layer 180 c may comprise Ti, Ni, Cr, Pt, TiW, W, or Mo, or acombination thereof. The barrier layer 180 c may prevent the reflectiveconductive layer 180 b from being damaged in the subsequent etchingprocess or cleaning process. The barrier layer 180 c may be formed of asingle layer or a multilayer and may be formed to have a thicknessranging from 300 μm to 5000 μm.

When the first semiconductor layers 111, 112, 113, and 114 have then-type conductivity and the second semiconductor layers 131, 132, 133,and 134 have the p-type conductivity, each of the upper electrodes maybe modeled as the cathode electrode of the light emitting diode and maybe simultaneously modeled as wiring for connecting the cathode electrodeof the light emitting diode to the lower electrode that is the anodeelectrode of the light emitting diode formed in the adjacent cellregions. In the light emitting diode formed in the cell region, theupper electrode may be modeled as the wiring for electrically connectingthe cathode electrode of the light emitting diode to the anode electrodeof the light emitting diode in the adjacent cell regions while formingthe cathode electrode.

FIG. 50 is a perspective view of the structure in the plan view of FIG.45 .

Referring to FIG. 50 , the first to third upper electrodes 181 to 183are formed over at least two cell regions. Thus, the space betweenadjacent cell regions is shielded. The upper electrodes allow light,which may be leaked between the adjacent cell regions, to be reflectedthrough the substrate, and are electrically connected to the firstsemiconductor layer in each of the cell regions. Further, the upperelectrodes are electrically connected to the second semiconductor layerin an adjacent cell region.

FIG. 51 is an equivalent circuit diagram obtained by modeling thestructure of FIGS. 45 to 50 according to one embodiment of the presentdisclosure.

Referring to FIG. 51 , four light emitting diodes D1, D2, D3 and D4 anda wiring relationship among the light emitting diodes are shown.

The first light emitting diode D1 is formed in the first cell region161, the second light emitting diode D2 is formed in the second cellregion 162, the third light emitting diode D3 is formed in the thirdcell region 163, and the fourth light emitting diode D4 is formed in thefourth cell region 164. Further, the first semiconductor layers 111,112, 113 and 114 in the respective cell regions 161, 162, 163 and 164are modeled as the n-type semiconductors, and the second semiconductorlayers 131, 132, 133 and 134 are modeled as the p-type semiconductors.

The first upper electrode 181 is electrically connected to the firstsemiconductor layer in the first cell region 161 and extends to thesecond cell region 162 so as to be electrically connected to the secondsemiconductor layer in the second cell region 162. Thus, the first upperelectrode 181 is modeled as wiring for connecting the cathode terminalof the first light emitting diode D1 to the anode terminal of the secondlight emitting diode D2.

Further, the second upper electrode 182 is modeled as wiring forconnection between the cathode terminal of the second light emittingdiode D2 and the anode terminal of the third light emitting diode D3 andthe third upper electrode 183 is modeled as wiring for connectionbetween the cathode terminal of the third light emitting diode D3 andthe anode terminal of the fourth light emitting diode D4. Further, thefourth upper electrode 184 is modeled as wiring for forming the cathodeterminal of the fourth light emitting diode D4.

Thus, the anode terminal of the first light emitting diode D1 and thecathode terminal of the fourth light emitting diode D4 are in anelectrically opened state with respect to an external power source, andthe other light emitting diodes D2 and D3 have a serially connectedstructure.

FIG. 52 is a plan view showing that the second interlayer insulatinglayer is applied on the entire surface of the structure in the plan viewof FIG. 45 , a portion of the first lower electrode in the first cellregion is exposed through the second via hole structures, and a portionof the fourth lower electrode in the fourth cell region is exposedthrough the third via hole structures.

FIG. 53 is a sectional view taken along line B1-B2 in the plan view ofFIG. 52 , FIG. 54 is a sectional view taken along line C1-C2 in the planview of FIG. 52 , FIG. 55 is a sectional view taken along line D1-D2 inthe plan view of FIG. 52 , and FIG. 56 is a sectional view taken alongline E1-E2 in the plan view of FIG. 52 .

Referring to FIG. 53 , the first lower electrode 151 electricallyconnected to the second semiconductor layer 131 in the first cell region161 is opened. The remaining portions in the first cell region arecovered with the second interlayer insulating layer 190 that is alsoformed over the second cell region 162.

Referring to FIG. 54 , the second and third cell regions 162 and 163 arecovered with the second interlayer insulating layer 190.

Further, referring to FIGS. 52, 55, and 56 , the fourth upper electrode184 in the fourth cell region 164 is exposed through third via holestructures 184 h, and the first lower electrode 151 in the first cellregion 161 is exposed through the second via hole structures 151 h. Thesecond via hole structures 151 h may be formed by reopening the secondinterlayer insulating layer 190 covered on the second via holestructures through the first interlayer insulating layer 170.

In the present embodiment, similar to the second via hole structures 151h, the third via hole structures 184 h may be disposed at both sides ofthe first via hole structures. At least two of the third via holestructures 184 h may be disposed apart by a predetermined distance fromthe underlying first via hole structures. In some implementations, whenviewing the fourth cell region 164 from the top, two of the third viahole structures 184 h may be disposed to be vertically symmetrical inthe first cell region. In some implementations, the third via holestructures 184 h may be disposed apart by a predetermined distance fromone distal end of the first via hole structure. As described above, thefirst via hole structures may be formed to include the pair of via holesdisposed at distal ends of the first via hole structures and theconnection parts connecting between the pair of via holes and one of thepair of via holes may be disposed apart by a predetermined distance fromthe four third via hole structures 184 h as illustrated in FIG. 52 .

In the present disclosure, the fourth upper electrodes 184 exposedthrough the third via hole structures 184 h may be electricallyconnected to the outside through the second pad later. The third viahole structures and the underlying first via hole structures keep aregularly spaced state at a predetermined distance from each other andtherefore it is possible to easily diffuse a current in the lightemitting diode. The third via hole structures may be disposed in aregular form with column and row in consideration of the underlyingfirst via hole structures and therefore the flow of current in the lightemitting diode may be uniform.

The second interlayer insulating layer 190 is selected from or includesan insulation material capable of protecting an underlying film from anexternal environment. In some implementations, the second interlayerinsulating layer may comprise SiN or the like that has an insulationproperty and can block a change in temperature or humidity.

In FIGS. 52 to 56 , the second interlayer insulating layer 190 isapplied over the structure of the substrate. Further, portions of thefirst lower electrode 151 in the first cell region 161 are exposedthrough the first via hole structures 151 h, and the fourth upperelectrode 184 in the fourth cell region 164 is exposed through the thirdvia hole structures 184 h.

FIG. 57 is a plan view showing that the first and second pads are formedin the structure of FIG. 52 .

Referring to FIG. 57 , the first pad 210 may be formed over the firstand second cell regions 161 and 162. Accordingly, the first pad 210 canbe electrically connected to the first lower electrode 151 in the firstcell region 161, which is exposed in FIG. 52 .

Moreover, the second pad 220 is formed to be spaced apart from the firstpad 210 at a predetermined distance, and may be formed over the thirdand fourth cell regions 163 and 164. The second pad 220 is electricallyconnected to the fourth upper electrode 184 in the fourth cell region164, which is exposed through the third via hole structures 184 h inFIG. 52 .

FIG. 58 is a sectional view taken along line B1-B2 in the plan view ofFIG. 57 , FIG. 59 is a sectional view taken along line C1-C2 in the planview of FIG. 57 , FIG. 60 is a sectional view taken along line D1-D2 inthe plan view of FIG. 57 , and FIG. 61 is a sectional view taken alongline E1-E2 in the plan view of FIG. 57 .

Referring to FIG. 58 , the first pad 210 may be formed over the firstand second cell regions 161 and 162. The first pad 210 is formed on thefirst lower electrode 151 exposed in the first cell region 161. Thefirst pad 210 is formed on the second interlayer insulating layer 190 inthe remaining region. Thus, the first pad 210 is electrically connectedto the second semiconductor layer 131 in the first cell region 161through the first lower electrode 151.

Referring to FIG. 59 , the first pad 210 is formed in the second cellregion 162, and the second pad 220 is formed to be spaced apart from thefirst pad 210 in the third cell region 163. The electrical contact ofthe first or second pad 210 or 220 with the lower or upper electrode isblocked in the second and third cell regions 162 and 163.

Referring to FIG. 60 , the second pad 220 may be formed over the thirdand fourth cell regions 163 and 164. In some implementations, the fourthupper electrode 184 and the second pad 220 which are opened in thefourth cell region 164 are electrically connected to each other. Thus,the second pad 220 is electrically connected to the first semiconductorlayer 114 in the fourth cell region 164.

Referring to FIG. 61 , the second pad 220 is formed in the fourth cellregion 164, and the first pad 210 is formed to be spaced apart from thesecond pad 220 in the first cell region 161. The first pad 210 is formedon the first lower electrode 151 in the first cell region 161 to beelectrically connected to the second semiconductor layer 131.

FIG. 62 is a perspective view showing the structure in the plan view ofFIG. 57 and FIG. 63 is a sectional view taken along line C2-C3 in theperspective view of FIG. 62 .

Referring to FIGS. 62 and 63 , the first semiconductor layer 113 in thethird cell region 163 is electrically connected to the third upperelectrode 183. The third upper electrode 183 shields the space betweenthe third and fourth cell regions 163 and 164 and is electricallyconnected to the fourth lower electrode 154 in the fourth cell region164. Further, the first and second pads 210 and 220 are spaced apartfrom each other and formed on the second interlayer insulating layer190. As described above, the first pad 210 is electrically connected tothe second semiconductor layer 131 in the first cell region 161, and thesecond pad 220 is electrically connected to the first semiconductorlayer 114 in the fourth cell region 164.

Referring to the modeling of FIG. 51 , the first semiconductor layers111, 112, 113 and 114 in the respective cell regions are modeled as then-type semiconductors, and the second semiconductor layers 131, 132, 133and 134 are modeled as the p-type semiconductors. The first lowerelectrode 151 formed on the second semiconductor layer 131 in the firstcell region 161 is modeled as the anode electrode of the first lightemitting diode D1. Therefore, the first pad 210 may be modeled as thewiring connected to the anode electrode of the first light emittingdiode D1. Further, the fourth upper electrode 184 electrically connectedto the first semiconductor layer 114 in the fourth cell region 164 ismodeled as the cathode electrode of the fourth light emitting diode D4.Therefore, the second pad 220 may be understood as the wiring connectedto the cathode electrode of the fourth light emitting diode D4.

Accordingly, the array structure in which the four light emitting diodesD1 to D4 are connected in series is formed, and the electricalconnection of the array structure to the outside is achieved through thetwo pads 210 and 220 formed on the single substrate 100.

In the present disclosure, there is shown that the four light emittingdiodes are formed while being separated from one another and the anodeterminal of one of the light emitting diodes is electrically connectedto the cathode terminal of another light emitting diode through thelower and upper electrodes. However, the four light emitting diodes inthis embodiment are merely an example, and various numbers of lightemitting diodes according to the present disclosure may be formed.

FIG. 64 is a schematic perspective view showing a light emitting diodemodule including a light emitting diode array according to an embodimentof the present disclosure.

Referring to FIG. 64 , the light emitting diode module comprises aprinted circuit board 250 having pads 240 and the light emitting diodearray 200 bonded to the printed circuit board 250 through a solder paste230.

The printed circuit board is or includes a substrate on which theprinted circuit is formed. Any substrate may be used as long as itprovides the light emitting diode module.

The light emitting diode array 200 is mounted on the printed circuitboard 250 while being overturned in a flip chip form. The light emittingdiode array 200 is mounted on the printed circuit board 250 through thefirst and second pads 210 and 220. A lower surface of the light emittingdiode array 200, for example, a light extraction surface of thesubstrate 100 may be covered with a wavelength converter (not shown).The wavelength converter may cover the upper surface and a side of thelight emitting diode array 200.

FIG. 65 is a circuit diagram obtained by modeling a connection of tenlight emitting diodes in series according to an embodiment of thepresent disclosure.

Referring to FIG. 65 , ten cell regions 301 to 310 are defined using theprocess shown in FIG. 37 . The first semiconductor layer, the activelayer, the second semiconductor layer and the lower electrode in each ofthe cell regions 301 to 310 are separated from those in other cellregions. The respective lower electrodes are formed on the secondsemiconductor layers so as to form the anode electrodes of lightemitting diodes D1 to D10.

The first interlayer insulating layer and the first to tenth upperelectrodes 181 to 189 and 189′ are formed using the processes shown inFIGS. 38 to 49 . However, the formed upper electrodes 181 to 189 and189′ shield the space between the adjacent cell regions. The first toninth upper electrodes 181 to 189 serve as wiring for achieving theelectrical connection between the anode electrodes of one side of thepair of adjacent light emitting diodes and the first semiconductor layerof the other side of the pair of adjacent light emitting diodes.Furthermore, the tenth upper electrode 189′ is electrically connected tothe first semiconductor layer of the light emitting diode D10.

Furthermore, the second interlayer insulating layer is formed using theprocesses shown in FIGS. 52 to 61 . The lower electrode of the firstlight emitting diode D1 connected to a positive power voltage V+ on acurrent path is exposed, and the upper electrode of the tenth lightemitting diode D10 connected to a negative power voltage V− on thecurrent path is opened. Then, a first pad 320 is formed and connected tothe anode terminal of the first light emitting diode D1. Further, asecond pad 330 is formed and connected to the cathode terminal of thetenth light emitting diode D10.

In some implementations, other light emitting diodes are connected inseries/parallel so as to form an array.

FIG. 66 is a circuit diagram obtained by modeling the array having lightemitting diodes connected in series/parallel according to an embodimentof the present disclosure.

Referring to FIG. 66 , the plurality of light emitting diodes D1 to D8are connected in parallel to the adjacent light emitting diodes whilehaving the serial connection. Each of the light emitting diodes D1 to D8is formed independently through the definitions of cell regions 401 to408. As described above, the anode electrodes of each of the lightemitting diodes D1 to D8 are formed through the lower electrode. Thewirings between the cathode electrodes of the light emitting diodes D1to D8 and the anode electrodes of the adjacent light emitting diodes aremade by forming the upper electrodes and performing an appropriatewiring process. However, the lower electrode is formed on the secondsemiconductor layer, and the upper electrode is formed to shield thespace between the adjacent cell regions.

A first pad 410 supplied with a positive power voltage V+ iselectrically connected to the lower electrode formed on the secondsemiconductor layer of the first or third light emitting diode D1 or D3,and a second pad 420 supplied with a negative power voltage V− iselectrically connected to the upper electrode that is the cathodeelectrode of the sixth or eighth light emitting diode D6 or D8.

According to the present disclosure described above, the light generatedin the active layer of each of the light emitting diodes is reflectedfrom the lower and upper electrodes toward the substrate, and theflip-chip type light emitting diodes are electrically connected throughwiring of the upper electrodes on the single substrate. The upperelectrode serves as the wiring for achieving the electrical connectionbetween the first semiconductor layer of one side of the pair ofadjacent light emitting diodes and the second semiconductor layer of theother side of the pair of adjacent light emitting diodes. In this case,the upper electrode includes the reflective conductive layer to reflectthe light emitted from the light emitting layer, thereby increasing thelight extraction efficiency.

The upper electrode is shielded from the outside through the secondinterlayer insulating layer. The first pad supplied with a positivepower voltage is electrically connected to the lower electrode of thelight emitting diode connected most closely to the positive powervoltage. Further, the second pad supplied with a negative power voltageis electrically connected to the upper electrode of the light emittingdiode connected most closely to the negative power voltage.

Thus, it is possible to avoid inconvenience in a process of mounting aplurality of flip-chip type light emitting diodes on a submountsubstrate and implementing two terminals to an external power sourcethrough wiring arranged on the submount substrate. In addition, thespace between adjacent cell regions can be shielded by the upperelectrode, thereby maximizing the reflection of light toward thesubstrate.

Further, the second interlayer insulating layer protects the pluralityof laminated structures, which are arranged between the substrate andthe second interlayer insulating layer, from external temperature orhumidity and the like. Thus, it is possible to implement a structurethat can be directly mounted on a substrate without intervention of anyseparate packaging means.

In particular, since the plurality of flip-chip type light emittingdiodes are implemented on the single substrate, there is an advantage inthat the commercial power source can be directly used while excludingthe voltage drop, the conversion of the voltage level or the conversionof waveform for the commercial power source supplied.

Further, it is possible to effectively diffuse a current by providingthe suitable form of the first via hole structures included in the lightemitting diode array, the suitable mutual disposition form between thefirst via hole structures and the second via hole structures, and thesuitable mutual disposition form between the first via holes and thethird via holes.

FIGS. 67 and 68 are plan and sectional views showing that a plurality ofvia holes are formed in a laminated structure according to an embodimentof the present disclosure.

In particular, FIG. 68 is a sectional view taken along line A1-A2 in theplan view of FIG. 67 .

Referring to FIGS. 67 and 68 , a first semiconductor layer 110, anactive layer 120 and a second semiconductor layer 130 are formed on asubstrate 100, and via holes 140 are formed to allow a surface of thesemiconductor layer 110 to be exposed therethrough.

The substrate 100 comprises a material such as sapphire, silicon carbideor GaN. Any material may be used for the substrate 100 as long as it caninduce the growth of a thin film to be formed on the substrate 100. Thefirst semiconductor layer 110 may have n-type conductivity. The activelayer 120 may have a multiple quantum well structure, and the secondsemiconductor layer 130 is formed on the active layer 120. When thefirst semiconductor layer 110 has the n-type conductivity, the secondsemiconductor layer 130 has p-type conductivity. A buffer layer (notshown) may be further formed between the substrate 100 and the firstsemiconductor layer 110 so as to facilitate single crystalline growth ofthe first semiconductor layer 110.

Subsequently, selective etching is performed on the structure formedwith up to the second semiconductor layer 130, and a plurality of viaholes 140 are formed. Portions of the lower first semiconductor layer110 are exposed through the via holes 140. The via holes 140 may beformed through a conventional etching process. For example, aphotoresist is applied, and portions of the photoresist on regions wherethe via holes will be formed are then removed through a conventionalpatterning process to form a photoresist pattern. Thereafter, an etchingprocess is performed by using the photoresist pattern as an etchingmask. The etching process is performed until the portions of the firstsemiconductor layer 110 are exposed. After the etching process, theremaining photoresist pattern is removed.

The shape and number of the via holes 140 may be variously changed.

FIGS. 69 and 70 are plan and sectional views showing that lowerelectrodes are formed on the second semiconductor layer 130 of FIG. 67 .Particularly, FIG. 70 is a sectional view taken along line A1-A2 in theplan view of FIG. 69 .

Referring to FIGS. 69 and 70 , the lower electrodes 151, 152, 153 and154 are formed in regions except the via holes 140, and a plurality ofcell regions 161, 162, 163 and 164 may be defined by the formation ofthe lower electrodes 151, 152, 153 and 154. The lower electrodes 151,152, 153 and 154 may be formed by employing a lift-off process used uponformation of a metal electrode. For example, a photoresist is formed inseparating regions excluding the virtual cell regions 161, 162, 163 and164 and in the regions in which the via holes 140 are formed, and ametal layer is formed through conventional thermal deposition or thelike. Subsequently, the photoresist is removed, thereby forming thelower electrodes 151, 152, 153 and 154 on the second semiconductor layer130. Any material may be employed for the lower electrodes 151, 152, 153and 154 as long as it is a metallic material capable of being in ohmiccontact with the second semiconductor layer 130. The lower electrodes151, 152, 153 and 154 may include a reflective layer of a material suchas Al, Ag, Rh or Pt. For example, the lower electrodes 151, 152, 153 and154 may comprise Ni, Cr or Ti, and may be composed of a composite metallayer of Ti/Al/Ni/Au.

In FIGS. 69 and 70 , the regions in which the four lower electrodes 151,152, 153 and 154 are formed define four cell regions 161, 162, 163 and164, respectively. The second semiconductor layer 130 is exposed inspaces among the cell regions 161, 162, 163 and 164. The number of thecell regions 161, 162, 163 and 164 may correspond to that of lightemitting diodes included in an array to be formed. Therefore, the numberof the cell regions 161, 162, 163 and 164 may be variously changed.

Although FIG. 70 shows that the lower electrode 151, 152, 153 or 154 isseparated in the same cell region 161, 162, 163 or 164, this is aphenomenon occurring as line A1-A2 transverses the via holes 140. As canbe seen in FIG. 69 , the lower electrode 151, 152, 153 or 154 formed inthe same cell region 161, 162, 163 or 164 is physically continuous.Thus, the lower electrode 151, 152, 153 or 154 formed in the same cellregion is in an electrically short-circuited state even though the viaholes 140 are formed therein.

FIG. 71 is a plan view showing a state where cell regions are separatedwith respect to the structure of FIG. 69 , FIG. 72 is a sectional viewtaken along line A1-A2 in the plan view of FIG. 71 , and FIG. 73 is aperspective view of the structure in the plan view of FIG. 71 .

Referring to FIGS. 71, 72 and 73 , mesa-etched regions are formedthrough mesa etching for the spaces among the four cell regions 161,162, 163 and 164. The substrate 100 is exposed in the mesa-etchedregions formed through the mesa etching. Thus, the four cell regions161, 162, 163 and 164 are electrically isolated, or completely separatedfrom one another. If a buffer layer is interposed between the substrate100 and the first semiconductor layer 110 in FIGS. 67 to 70 , the bufferlayer may remain even in the separation process of the cell regions 161,162, 163 and 164. However, in order to completely separate the cellregions 161, 162, 163 and 164 from one another, the buffer layer betweenadjacent ones of the cell regions 161, 162, 163 and 164 may be removedthrough the mesa etching.

With the separation process between adjacent ones of the cell regions161, 162, 163 and 164, first semiconductor layers 111, 112, 113 and 114,active layers 121, 122, 123 and 124, second semiconductor layers 131,132, 133 and 134 and lower electrodes 151, 152, 153 and 154 areindependently formed in the cell regions 161, 162, 163 and 164,respectively. Thus, the first lower electrode 151 is exposed in thefirst cell region 161, and the first semiconductor layer 111 is exposedthrough the via holes 140. The second lower electrode 152 is exposed inthe second cell region 162, and the first semiconductor layer 112 isexposed through the via holes 140. Similarly, the third lower electrode153 and the first semiconductor layer 113 are exposed in the third cellregion 163, and the fourth lower electrode 154 and the firstsemiconductor layer 114 are exposed in the fourth cell region 164.

In some embodiments, the light emitting diode may correspond to astructure in which the first semiconductor layer 111, 112, 113 or 114,the active layer 121, 122, 123 or 124 and the second semiconductor layer131, 132, 133 or 134 are laminated, respectively. Thus, one lightemitting diode is formed in one cell region. When the light emittingdiode is modeled such that the first semiconductor layer 111, 112, 113or 114 has n-type conductivity and the second semiconductor layer 131,132, 133 or 134 has p-type conductivity, the lower electrode 151, 152,153 or 154 formed on the second semiconductor layer 131, 132, 133 or 134may be referred to as an anode electrode of the light emitting diode.

FIG. 74 is a plan view showing that a first interlayer insulating layeris formed on an entire surface of the structure of FIGS. 71 to 73 , andportions of a first semiconductor layer and the lower electrodes areexposed in each of the cell regions.

Moreover, FIGS. 75 to 78 are sectional views taken along specific linesin the plan view of FIG. 74 . Particularly, FIG. 75 is a sectional viewtaken along line B1-B2 in the plan view of FIG. 74 , FIG. 76 is asectional view taken along line C1-C2 in the plan view of FIG. 74 , FIG.77 is a sectional view taken along line D1-D2 in the plan view of FIG.74 , and FIG. 78 is a sectional view taken along line E1-E2 in the planview of FIG. 74 .

First, a first interlayer insulating layer 170 is formed with respect tothe structure of FIGS. 71 to 73 . Moreover, portions of the lowerelectrodes 151, 152, 153 and 154 and of the first semiconductor layers111, 112, 113 and 114 under the via holes are exposed by means ofpatterning.

For example, in the first cell region 161, two pre-formed via holes areopened so that portions of the first semiconductor layer 111 areexposed, and a portion of the first lower electrode 151 formed on thepre-formed second semiconductor layer 131 is exposed. In the second cellregion 162, portions of the first semiconductor layer 112 are exposedthrough the pre-formed via holes, and a portion of the second lowerelectrode 152 is exposed by means of etching for a portion of the firstinterlayer insulating layer 170. In the third cell region 163, portionsof the first semiconductor layer 113 are exposed through the via holes,and a portion of the third lower electrode 153 is exposed by means ofetching for a portion of the first interlayer insulating layer 170. Inthe fourth cell region 164, portions of the first semiconductor layer114 are exposed through the via holes, and a portion of the fourth lowerelectrode 154 is exposed by means of etching for a portion of the firstinterlayer insulating layer 170.

As a result, in FIGS. 74 to 78 , the first interlayer insulating layer170 is formed on the entire surface of the substrate, and the portionsof the first semiconductor layers 111, 112, 113 and 114 under the viaholes and the portions of the lower electrodes 151, 152, 153 and 154 onthe second semiconductor layers 131, 132, 133 and 134 are exposed ineach of the cell regions 161, 162, 163 and 164 by means of selectiveetching. That is, in the respective cell regions 161, 162, 163 and 164,the portions of the first semiconductor layers 111, 112, 113 and 114 areexposed through the via holes previously formed in the precedingprocess, and the portions of the lower electrodes 151, 152, 153 and 154are also exposed. The remaining region is shielded by the firstinterlayer insulating layer 170. The first interlayer insulating layer170 may be formed of an insulating material having a lighttransmittance. For example, the first interlayer insulating layer maycomprise SiO₂. Alternatively, the first interlayer insulating layer 170may be formed as a distributed Bragg reflector in which material layershaving different refractive indices are laminated. For example, thefirst interlayer insulating layer 170 can be formed by repetitivelylaminating SiO₂/TiO₂, thereby reflecting light generated from the activelayer.

FIG. 79 is a plan view showing an embodiment in which upper electrodesare formed on the structure illustrated in FIGS. 74 to 78 . FIGS. 80 to83 are sectional views taken along specific lines in the plan view ofFIG. 79 . Particularly, FIG. 80 is a sectional view taken along lineB1-B2 in the plan view of FIG. 79 , FIG. 81 is a sectional view takenalong line C1-C2 in the plan view of FIG. 79 , FIG. 82 is a sectionalview taken along line D1-D2 in the plan view of FIG. 79 , and FIG. 83 isa sectional view taken along line E1-E2 in the plan view of FIG. 79 .

Referring to FIG. 79 , upper electrodes 181, 182, 183 and 184 areillustrated. The upper electrodes 181, 182, 183 and 184 are formed asfour discrete regions. For example, the first upper electrode 181 isformed over the first cell region 161 and a portion of the second cellregion 162. The second upper electrode 182 is formed over a portion ofthe second cell region 162 and a portion of the third cell region 163.The third upper electrode 183 is formed over a portion of the third cellregion 163 and a portion of the fourth cell region 164. The fourth upperelectrode 184 is formed in a portion of the fourth cell region 164.Thus, each of the upper electrodes 181, 182, 183 and 184 is formed whileshielding spaces between adjacent ones of the cell regions. The upperelectrodes 181, 182, 183 and 184 may cover no less than 30%, even noless than 50%, or no less than 90% of the spaces between the adjacentcell regions. However, since the upper electrodes 181, 182, 183 and 184are spaced apart from one another, the upper electrodes 181, 182, 183and 184 cover less than 100% of regions between adjacent ones of lightemitting diodes.

The entirety of the upper electrodes 181, 182, 183 and 184 may occupy noless than 30%, no less than 50%, no less than 70%, no less than 80% orno less than 90% of the entire area of the light emitting diode array.However, since the upper electrodes 181, 182, 183 and 184 are spacedapart from one another, they occupy less than 100% of the entire area ofthe light emitting diode array. Each of the upper electrodes 181, 182,183 and 184 may have the shape of a plate or sheet having a ratio oflength and width ranging from 1:3 to 3:1. Further, at least one of theupper electrodes 181, 182, 183 and 184 has a length or width greaterthan that of a corresponding light emitting diode (cell region).

Referring to FIG. 80 , the first upper electrode 181 is formed on thefirst interlayer insulating layer 170 in the first cell region 161, andis formed on portions of the first semiconductor layer 111 openedthrough the via holes. In addition, the first upper electrode 181 allowsa portion of the first lower electrode 151 to be opened in the firstcell region 161 and is formed on a portion of the second lower electrode152 exposed in the second cell region 162.

The second upper electrode 182 is formed on portions of the firstsemiconductor layer 112 exposed through the via holes in the second cellregion 162 in a state in which the second upper electrode 182 isphysically separated from the first upper electrode 181. In addition,the second upper electrode 182 is formed on the first interlayerinsulating layer 170.

In FIG. 80 , the first upper electrode 181 electrically connects thefirst semiconductor layer 111 in the first cell region 161 to the secondsemiconductor layer 132 in the second cell region 162. Despite of thepresence of the via holes, the second lower electrode 152 in the secondcell region 162 is entirely in an electrically short-circuited state inone cell region. Thus, the first semiconductor layer 111 in the firstcell region 161 is electrically connected to the second semiconductorlayer 132 in the second cell region 162 through the second lowerelectrode 152.

In FIG. 81 , the second upper electrode 182 is formed on portions of thefirst semiconductor layer 112 exposed through the via holes in thesecond cell region 162, and is formed to extend to the third lowerelectrode 153 in the third cell region 163. The third upper electrode183 physically separated from the second upper electrode 182 is alsoformed on portions of the first semiconductor layer 113 exposed throughthe via holes in the third cell region 163.

In FIG. 81 , the second upper electrode 182 is electrically connected tothe portions of the first semiconductor layer 112 through the via holesin the second cell region 162, and is electrically connected to thethird lower electrode 153 in the third cell region 163. Thus, the firstsemiconductor layer 112 in the second cell region 162 can maintain thesame potential as the second semiconductor layer 133 in the third cellregion 163.

Referring to FIG. 82 , the third upper electrode 183 is formed onportions of the first semiconductor layer 113 exposed through the viaholes in the third cell region 163, and is formed to extend to thefourth lower electrode 154 in the fourth cell region 164. Thus, thefirst semiconductor layer 113 in the third cell region 163 iselectrically connected to the second semiconductor layer 134 in thefourth cell region 164. The fourth upper electrode 184 physicallyseparated from the third upper electrode 183 is electrically connectedto the portions of the first semiconductor layer 114 exposed through thevia holes in the fourth cell region 164.

Referring to FIG. 83 , the fourth upper electrode 184 is formed onportions of the first semiconductor layer 114 exposed through the viaholes in the fourth cell region 164. The first upper electrode 181physically separated from the fourth upper electrode 184 is formed onportions of the first semiconductor layer 111 exposed through the viaholes in the first cell region 161, and allows a portion of the firstlower electrode 151 to be exposed in the first cell region 161.

Some features illustrated in FIGS. 79 to 83 will be summarized below.The first semiconductor layer 111 in the first cell region 161 and thesecond semiconductor layer 132 in the second cell region 162 establishthe same potential through the first upper electrode 181. The firstsemiconductor layer 112 in the second cell region 162 and the secondsemiconductor layer 133 in the third cell region 163 establish the samepotential through the second upper electrode 182. The firstsemiconductor layer 113 in the third cell region 163 establish the samepotential as the second semiconductor layer 134 in the fourth cellregion 164 through the third upper electrode 183. The first lowerelectrode 151 electrically connected to the second semiconductor layer131 in the first cell region 161 is exposed.

Of course, the same potential is established by assuming idealelectrical connection in a state where resistances of the upperelectrodes 181, 182, 183 and 184 and contact resistances between theupper electrodes 181, 182, 183 and 184 and the lower electrodes 151,152, 153 and 154 are neglected. Thus, in the operation of an actualdevice, a voltage drop may be sometimes caused by resistance componentsof the upper electrodes 181, 182, 183 and 184 and the lower electrodes151, 152, 153 and 154, which are kinds of metal wires.

Meanwhile, the upper electrodes 181, 182, 183 and 184 may include areflective conductive layer 180 b. The reflective conductive layer 180 bmay comprise Al, Ag, Rh, Pt or a combination thereof. The upperelectrodes 181, 182, 183 and 184 including the reflective conductivelayer 180 b may reflect light, which is generated from the active layers121, 122, 123 and 124 in the respective cell regions 161, 162, 163 and164, toward the substrate 100. Further, the upper electrodes 181, 182,183 and 184 may construct, together with the first interlayer insulatinglayer 170, omni-directional reflectors. Meanwhile, even when the firstinterlayer insulating layer 170 is formed as the distributed Braggreflector, the upper electrodes 181, 182, 183 and 184 including thereflective conductive layer 180 b can also improve light reflectivity.

The upper electrodes 181, 182, 183 and 184 may also include an ohmiccontact layer 180 a. The reflective conductive layer 180 b may bepositioned on the ohmic contact layer 180 a. The ohmic contact layer 180a comprises a material, such as Ni, Cr, Ti, Rh, Al or combinationthereof, that can be in ohmic contact with the first semiconductorlayers 111, 112, 113 and 114 and the lower electrodes 151, 152, 153 and154. However, the ohmic contact layer 180 a is not limited thereto, andany material may be used for the ohmic contact layer 180 a as long as itis a material that can be in ohmic contact with the lower electrodes151, 152, 153 and 154 made of a metallic material while being in ohmiccontact with the first semiconductor layers 111, 112, 113 and 114. Alayer of conductive oxide such as ITO may be used.

The light generated from the active layers 121, 122, 123 and 124 in therespective cell regions 161, 162, 163 and 164 may be reflected from thelower electrodes 151, 152, 153 and 154 toward the substrate 100. Inaddition, light transmitted through the spaces between the adjacent onesof the cell regions 161, 162, 163 and 164 is reflected by the firstinterlayer insulating layer 170 shielding the spaces between theadjacent ones of the cell regions 161, 162, 163 and 164 and/or the upperelectrodes 181, 182, 183 and 184. The light L generated from the activelayers 121, 122, 123 and 124 and directed to the via holes or the spacesbetween the adjacent ones of the cell regions 161, 162, 163 and 164 isreflected by the first interlayer insulating layer 170 disposed onsidewalls of the via holes or spaces and/or by the upper electrodes 181,182, 183 and 184 having the reflective conductive layer 180 b, so thatthe light can be extracted to the outside through the substrate 100.Accordingly, it is possible to reduce light loss, thereby improvinglight extraction efficiency.

To this end, it is preferable that the upper electrodes 181, 182, 183and 184 occupy a large area in the light emitting diode array. Forexample, the upper electrodes 181, 182, 183 and 184 may cover no lessthan 70%, no less than 80% or even no less than 90% of the entire areaof the light emitting diode array. An interval between the upperelectrodes 181, 182, 183 and 184 may be in a range of about 1 to 100 μm.More preferably, the interval between the upper electrodes 181, 182, 183and 184 may be 5 to 15 μm. Accordingly, it is possible to prevent lightleakage in the via holes or the spaces between the adjacent ones of thecell regions 161, 162, 163 and 164.

The upper electrodes 181, 182, 183 and 184 may further include a barrierlayer 180 c disposed on the reflective conductive layer 180 b. Thebarrier layer 180 c may comprise Ti, Ni, Cr, Pt, TiW, W, Mo or acombination thereof. The barrier layer 180 c can prevent the reflectiveconductive layer 180 b from being damaged during a subsequent etching orcleaning process. The barrier layer 180 c may be formed as a single- ormulti-layered structure and to have a thickness ranging from 300 to 5000μm.

If the first semiconductor layers 111, 112, 113 and 114 have n-typeconductivity and the second semiconductor layers 131, 132, 133 and 134have p-type conductivity, each of the upper electrodes may be modeled asa cathode electrode of the light emitting diode, and simultaneously aswiring for connecting the cathode electrode of the light emitting diodeto the lower electrode that is an anode electrode of a light emittingdiode formed in an adjacent cell region. That is, in the light emittingdiode formed in the cell region, the upper electrode may be modeled toform a cathode electrode and simultaneously to be wiring forelectrically connecting the cathode electrode of the light emittingdiode to an anode electrode of a light emitting diode in an adjacentcell region.

FIG. 84 is a perspective view of the structure in the plan view of FIG.79 .

Referring to FIG. 84 , the first to third upper electrodes 181 to 183are formed over at least two cell regions. The space between adjacentcell regions is shielded. The upper electrodes allow light, which may beleaked between adjacent cell regions, to be reflected through thesubstrate, and are electrically connected to the first semiconductorlayer in each cell region. The upper electrodes are electricallyconnected to the second semiconductor layer in an adjacent cell region.

FIG. 85 is an equivalent circuit diagram obtained by modeling thestructure of FIGS. 79 to 84 according to an embodiment of the presentdisclosure.

Referring to FIG. 85 , four light emitting diodes D1, D2, D3 and D4 anda wiring relationship among the light emitting diodes are shown.

The first light emitting diode D1 is formed in the first cell region161, the second light emitting diode D2 is formed in the second cellregion 162, the third light emitting diode D3 is formed in the thirdcell region 163, and the fourth light emitting diode D4 is formed in thefourth cell region 164. The first semiconductor layers 111, 112, 113 and114 in the cell regions 161, 162, 163 and 164 are modeled as n-typesemiconductors, and the second semiconductor layers 131, 132, 133 and134 are modeled as p-type semiconductors.

The first upper electrode 181 is electrically connected to the firstsemiconductor layer 111 in the first cell region 161 and extends to thesecond cell region 162 so as to be electrically connected to the secondsemiconductor layer 132 in the second cell region 162. Thus, the firstupper electrode 181 is modeled as wiring for connecting a cathodeterminal of the first light emitting diode D1 to an anode electrode ofthe second light emitting diode D2.

The second upper electrode 182 is modeled as wiring for connectionbetween a cathode terminal of the second light emitting diode D2 and ananode terminal of the third light emitting diode D3. The third upperelectrode 183 is modeled as wiring for connection between a cathodeelectrode of the third light emitting diode D3 and an anode terminal ofthe fourth light emitting diode D4. The fourth upper electrode 184 ismodeled as wiring for forming a cathode electrode of the fourth lightemitting diode D4.

Thus, the anode terminal of the first light emitting diode D1 and thecathode terminal of the fourth light emitting diode D4 are in anelectrically opened state with respect to an external power source, andthe other light emitting diodes D2 and D3 are electrically connected inseries.

FIG. 86 is a plan view showing that a second interlayer insulating layeris applied on an entire surface of the structure of FIG. 79 , a portionof the first electrode in the first cell region is exposed, and aportion of the fourth lower electrode in the fourth cell region isexposed.

FIG. 87 is a sectional view taken along line B1-B2 in the plan view ofFIG. 86 , FIG. 88 is a sectional view taken along line C1-C2 in the planview of FIG. 86 , FIG. 89 is a sectional view taken along line D1-D2 inthe plan view of FIG. 86 , and FIG. 90 is a sectional view taken alongline E1-E2 in the plan view of FIG. 86 .

Referring to FIG. 87 , in the first cell region 161, portions of thefirst lower electrode 151 electrically connected to the secondsemiconductor layer 131 are opened. The remaining portions in the firstcell region are covered with the second interlayer insulating layer 190that is also over the second cell region 162.

Referring to FIG. 88 , the second and third cell regions 162 and 163 arecompletely covered with the second interlayer insulating layer 190.

Referring to FIGS. 89 and 90 , portions of the fourth upper electrode184 in the fourth cell region 164 are exposed, and portions of the firstlower electrode 151 in the first cell region 161 are exposed.

The second interlayer insulating layer 190 is selected from aninsulation material capable of protecting an underlying film from anexternal environment. In particular, the second interlayer insulatinglayer may comprise SiN or the like that has an insulation property andcan block a change in temperature or humidity.

In FIGS. 86 to 90 , the second interlayer insulating layer 190 isapplied to the entire structure formed on the substrate, and alsoexposes a portion of the first lower electrode 151 in the first cellregion 161 and exposes the fourth upper electrode 184 in the fourth cellregion 164.

FIG. 91 is a plan view showing that first and second pads are formed inthe structure of FIG. 86 .

Referring to FIG. 91 , the first pad 210 may be formed over the firstand second cell regions 161 and 162. Accordingly, the first pad 210 canbe electrically connected to the first lower electrode 151 in the firstcell region 161, which is exposed in FIG. 86 .

Moreover, the second pad 220 is formed to be spaced apart from the firstpad 210 at a predetermined distance, and may be formed over the thirdand fourth cell regions 163 and 164. The second pad 220 is electricallyconnected to the fourth upper electrode 184 in the fourth cell region164, which is exposed in FIG. 86 .

FIG. 92 is a sectional view taken along line B1-B2 in the plan view ofFIG. 91 , FIG. 93 is a sectional view taken along line C1-C2 in the planview of FIG. 91 , FIG. 94 is a sectional view taken along line D1-D2 inthe plan view of FIG. 91 , and FIG. 95 is a sectional view taken alongline E1-E2 in the plan view of FIG. 91 .

Referring to FIG. 92 , the first pad 210 is formed over the first andsecond cell regions 161 and 162. The first pad 210 is formed on thefirst lower electrode 151 exposed in the first cell region 161, and onthe second interlayer insulating layer 190 in the other cell regions.Thus, the first pad 210 is electrically connected to the secondsemiconductor layer 131 in the first cell region 161 through the firstlower electrode 151.

Referring to FIG. 93 , the first pad 210 is formed in the second cellregion 162, and the second pad 220 is formed in the third cell region163 to be spaced apart from the first pad 210. The electrical contact ofthe first or second pad 210 or 220 with the lower or upper electrode isblocked in the second and third cell regions 162 and 163.

Referring to FIG. 94 , the second pad 220 is formed over the third andfourth cell regions 163 and 164. Particularly, the second pad 220 iselectrically connected to the fourth upper electrode 184 opened in thefourth cell region 164. Thus, the second pad 220 is electricallyconnected to the first semiconductor layer 114 in the fourth cell region164.

Referring to FIG. 95 , the second pad 220 is formed in the fourth cellregion 164, and the first pad 210 is formed to be spaced apart from thesecond pad 220 in the first cell region 161. The first pad 210 is formedon the first lower electrode 151 in the first cell region 161 andelectrically connected to the second semiconductor layer 131.

FIG. 96 is a perspective view taken along line C2-C3 in the plan view ofFIG. 91 .

Referring to FIG. 96 , the first semiconductor layer 113 in the thirdcell region 163 is electrically connected to the third upper electrode183. The third upper electrode 183 shields the space between the thirdand fourth cell regions 163 and 164 and is electrically connected to thefourth lower electrode 154 in the fourth cell region 164. The first andsecond pads 210 and 220 are spaced apart from each other and formed onthe second interlayer insulating layer 190. Of course, as describedabove, the first pad 210 is electrically connected to the secondsemiconductor layer 131 in the first cell region 161, and the second pad220 is electrically connected to the first semiconductor layer 114 inthe fourth cell region 164.

Referring to the modeling of FIG. 85 , the first semiconductor layers111, 112, 113 and 114 in the respective cell regions are modeled asn-type semiconductors, and the second semiconductor layers 131, 132, 133and 134 in the respective cell regions are modeled as p-typesemiconductors. The first lower electrode 151 formed on the secondsemiconductor layer 131 in the first cell region 161 is modeled as theanode electrode of the first light emitting diode D1. Thus, the firstpad 210 can be modeled as wiring connected to the anode electrode of thefirst light emitting diode D1. The fourth upper electrode 184electrically connected to the first semiconductor layer 114 in thefourth cell region 164 is modeled as the cathode electrode of the fourthlight emitting diode D4. Thus, the second pad 220 can be modeled aswiring connected to the cathode electrode of the fourth light emittingdiode D4.

Accordingly, an array structure in which the four light emitting diodesD1 to D4 are connected in series formed, and electrical connectionthereof to the outside is achieved through the two pads 210 and 220formed on the single substrate 100.

In the present disclosure, there is shown that the four light emittingdiodes are formed while being separated from one another and an anodeterminal of one of the light emitting diodes is electrically connectedto a cathode terminal of another of the light emitting diodes throughthe lower and upper electrodes. However, the four light emitting diodesin this embodiment are merely an example, and a various number of lightemitting diodes may be formed.

FIG. 97 is a circuit diagram obtained by modeling a connection of tenlight emitting diodes in series according to an embodiment of thepresent disclosure.

Referring to FIG. 97 , ten cell regions 301 to 310 are defined using theprocess shown in FIG. 71 . A first semiconductor layer, an active layer,a second semiconductor layer and a lower electrode in each of the cellregions 301 to 310 are separated from those in other cell regions. Therespective lower electrodes are formed on the second semiconductorlayers so as to form anode electrodes of light emitting diodes D1 toD10.

Subsequently, a first interlayer insulating layer and first to tenthupper electrodes 181, 182, 183, 184, 185, 186, 187, 188, 189 and 189′are formed using the processes shown in FIGS. 72 to 83 . The upperelectrodes 181, 182, 183, 184, 185, 186, 187, 188, 189 and 189′ shieldthe space between adjacent cell regions. The first to ninth upperelectrodes 181, 182, 183, 184, 185, 186, 187, 188 and 189 serve aswiring for achieving electrical connection between an anode electrode ofone of a pair of adjacent light emitting diodes and a firstsemiconductor layer of the other of the pair of adjacent light emittingdiodes. The tenth upper electrode 189′ is electrically connected to thefirst semiconductor layer of the light emitting diode D10.

Furthermore, a second interlayer insulating layer is formed using theprocesses shown in FIGS. 86 to 95 . The lower electrode of the firstlight emitting diode D1 connected to a positive power voltage V+ on acurrent path is exposed, and the upper electrode of the tenth lightemitting diode D10 connected to a negative power voltage V− on thecurrent path is opened. Then, a first pad 320 is formed and connected tothe anode terminal of the first light emitting diode D1, and a secondpad 330 is formed and connected to a cathode terminal of the tenth lightemitting diode D10.

The other light emitting diodes are connected in series/parallel so asto form an array.

FIG. 98 is a circuit diagram obtained by modeling an array having lightemitting diodes connected in series/parallel according to an embodimentof the present disclosure.

Referring to FIG. 98 , a plurality of light emitting diodes D1 to D8 areconnected in series and/or in parallel to one another. The lightemitting diodes D1 to D8 are formed independently of one another throughthe definitions of cell regions 401 to 408. As described above, an anodeelectrode of each of the light emitting diode D1 to D8 is formed througha lower electrode. Wiring between a cathode electrode of each of thelight emitting diodes D1 to D8 and the anode electrode of an adjacentlight emitting diode is made by forming an upper electrode andperforming an appropriate wiring process. However, the lower electrodeis formed on a second semiconductor layer, and the upper electrode isformed to shield the space between adjacent cell regions.

Finally, a first pad 410 supplied with a positive power voltage V+ iselectrically connected to the lower electrode formed on the secondsemiconductor layer of the first or third light emitting diode D1 or D3,and a second pad 420 supplied with a negative power voltage V− iselectrically connected to the upper electrode that is a cathodeelectrode of the sixth or eighth light emitting diode D6 or D8.

According to the present disclosure described above, light generated inthe active layer of each of the light emitting diodes is reflected fromthe lower and upper electrodes toward the substrate, and the flip-chiptype light emitting diodes are electrically connected through wiring ofthe upper electrodes on a single substrate. Specifically, the upperelectrode serves as wiring for achieving electrical connection betweenthe first semiconductor layer of one of a pair of adjacent lightemitting diodes and the second semiconductor layer of the other of thepair of adjacent light emitting diodes. In this case, the upperelectrode includes a reflective conductive layer, thereby reflectinglight emitted from a light-emitting layer to enhance light extractionefficiency.

In some embodiments, the upper electrode is shielded from the outsidethrough the second interlayer insulating layer. The first pad suppliedwith a positive power voltage is electrically connected to a lowerelectrode of a light emitting diode connected most closely to thepositive power voltage. The second pad supplied with a negative powervoltage is electrically connected to an upper electrode of a lightemitting diode connected most closely to the negative power voltage.

Thus, it is possible to solve inconvenience in a process of mounting aplurality of flip-chip type light emitting diodes on a submountsubstrate and implementing two terminals to an external power sourcethrough wiring arranged on the submount substrate. In addition, thespace between adjacent cell regions can be shielded by the upperelectrode, thereby maximizing the reflection of light toward thesubstrate.

Further, the second interlayer insulating layer protects a laminatedstructure, which is arranged between the substrate and the secondinterlayer insulating layer, from external temperature or humidity andthe like. Thus, it is possible to implement a structure that can bedirectly mounted on a substrate without intervention of any separatepackaging means.

In particular, since a plurality of flip-chip type light emitting diodescan be implemented on a single substrate, there is an advantage in thata commercial power source can be directly used without having toimplement a voltage drop, a conversion of voltage level or a conversionof waveform for the commercial power source.

Only a few embodiments, implementations and examples are described andother embodiments and implementations, and various enhancements andvariations can be made based on what is described and illustrated inthis document.

What is claimed is:
 1. A light emitting device, comprising: a substrate;a first light emitting diode and a second light emitting diode disposedon the substrate, each of the first and second light emitting diodeshaving a first semiconductor layer, an active layer, and a secondsemiconductor layer; a first upper electrode disposed on the secondlight emitting diode, electrically connected to the first light emittingdiode, and insulated from the second semiconductor layer of the firstlight emitting diode; and a second upper electrode disposed on thesecond light emitting diode, electrically connected to the second lightemitting diode, and insulated from the second semiconductor layer of thesecond light emitting diode, wherein the first light emitting diode andthe second light emitting diode are spaced apart from each other, suchthat a first portion of the substrate between the first and second lightemitting diodes does not overlap the first and second semiconductorlayers of the first and second light emitting diodes, wherein the firstlight emitting diode and the second light emitting diode have inclinedside surfaces facing each other with the first portion of the substratedisposed there between, respectively, wherein the first upper electrodehas a first portion electrically connected to the second semiconductorlayer of the second light emitting diode, and covering portions of thefirst portion of the substrate, the first light emitting diode, and thesecond light emitting diode, and wherein the second upper electrode hasa groove partially enclosing the first portion of the first upperelectrode in a plan view.
 2. The light emitting device of claim 1,wherein the second upper electrode is insulated from the first andsecond semiconductor layers of the first light emitting diode.
 3. Thelight emitting device of claim 1, wherein the first upper electrode hasa stepped structure.
 4. The light emitting device of claim 1, wherein atleast one of the first and second upper electrodes has a breadth orwidth greater than that of a corresponding light emitting diode.
 5. Thelight emitting device of claim 1, wherein the first upper electrode andthe second upper electrode include Al.
 6. The light emitting device ofclaim 1, wherein the first upper electrode and the second upperelectrode comprise ohmic contact layers in ohmic contact with the firstsemiconductor layers of the first and second light emitting diodes,respectively.
 7. The light emitting device of claim 1, wherein the firstupper electrode covers the inclined side surface of at least one of thefirst and second light emitting diodes.
 8. The light emitting device ofclaim 1, further comprising a first interlayer insulating layer disposedbetween the first and second light emitting diodes and the first andsecond upper electrodes, wherein the first and second upper electrodesare insulated from the side surfaces of the first and second lightemitting diodes by the first interlayer insulating layer.
 9. The lightemitting device of claim 8, further comprising lower electrodesrespectively disposed on the second semiconductor layers of the firstand second light emitting diodes, wherein the first interlayerinsulating layer exposes a portion of the lower electrode on the secondlight emitting diode, and wherein the first upper electrode is connectedto the lower electrode on the second light emitting diode exposedthrough the first interlayer insulating layer.
 10. The light emittingdevice of claim 9, further comprising a second interlayer insulatinglayer covering the first and second upper electrodes.
 11. The lightemitting device of claim 10, further comprising a first pad and a secondpad for supplying electrical power to the first and second lightemitting diodes, wherein the first and second pads are disposed on thesecond interlayer insulating layer.
 12. The light emitting device ofclaim 1, wherein the second upper electrode has a greater width than thefirst upper electrode in a plan view.
 13. The light emitting device ofclaim 1, wherein the first and second upper electrodes occupy at least30% and less than 100% of the entire area of the first and second lightemitting diodes.
 14. The light emitting device of claim 1, wherein thefirst upper electrode has a greater length than the second upperelectrode.
 15. The light emitting device of claim 1, wherein the grooveof the second upper electrode has a shape substantially complementary tothat of the first upper electrode in a plan view.
 16. The light emittingdevice of claim 15, wherein the second upper electrode has a protrusionformed near the groove.
 17. The light emitting device of claim 16,wherein the second upper electrode covers a greater area of the secondlight emitting diode than the first upper electrode.
 18. The lightemitting device of claim 1, wherein the substrate is a growth substratefor growing the first semiconductor layer, the active layer, and thesecond semiconductor layer.
 19. The light emitting device of claim 1,wherein the first light emitting diode or the second light emittingdiode has a via hole exposing the first semiconductor layer through thesecond semiconductor layer and the active layer, and wherein the firstupper electrode or the second upper electrode is electrically connectedto the first semiconductor layer through the via hole.
 20. The lightemitting device of claim 1, wherein at least a portion of the firstupper electrode is disposed on a same plane as the second upperelectrode.